Absolute Anime

I think I'm gonna split all this verb stuff into its own thread, since it shouldn't be part of the particle discussion.

PAST TENSE

Polite Positive
~masu changes to ~mashita (how easy is that?)
tabemasu (taberu) -> tabemashita (I ate)
oyogimasu (oyogu) -> oyogimashita (I swam)
kimasu (kuru) -> kimashita (it came)
desu (da) -> deshita (it was)
shimasu (suru) -> shimashita (I did it)
aimasu (au) -> aimashita (we met)

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Polite Negative
~masu changes to ~masen deshita
tabemasu -> tabemasen deshita (I didn't eat)
oyogu -> oyogimasen deshita (I didn't swim)
kuru -> kimasen deshita (it didn't come)
desu -> de wa arimasen deshita (it wasn't)

(Don't know if you know this...)
'desu' has several different forms for the present tense polite negative:
de wa arimasen, ja arimasen, de wa nai desu, ja nai desu.

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Informal Positive
This is probably the worst conjugation you'll have to learn. It gets easier once you get a feel for how natural pronounciation makes the words mutate.

RU verbs:
~ru changes to ~ta (this isn't the hard part yet!)
taberu -> tabeta (I ate)
miru (to see) -> mita ( I saw)
iru (to be/have) -> ita (I had/I was)

U verbs:
These are totally dependant on which letter precedes the final U.

If it's an R (aru, wakaru), the RU changes to TTA (atta, wakatta).
If it's a vowel (au, kau), the U also changes to TTA (atta, katta).
If it's a TS (matsu, motsu), the TSU also changes TTA (matta, motta).
(Notice that both 'aru' and 'au' conjugate the same way - you'll need to know which one it is by context.)

If it's an M (nomu, yomu), the MU changes to NDA (nonda, yonda).
If it's a B (asobu, yobu), the BU also changes to NDA (asonda, yonda).
If it's an N (shinu), the NU also changes to NDA (shinda).
(Notice once again that 'yomu' and 'yobu' conjugate the same way.)

If it's a K (kaku, hiku), the KU changes to ITA (kaita, hiita).

If it's a G (oyogu, mogu), the GU changes to IDA (oyoida, moida).

If it's an S (hanasu, dasu), the SU changes to SHITA (hanashita, dashita).

And, the irregular ones:
suru -> shita
kuru -> kita
desu/da -> datta
iku -> itta

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Informal Negative

RU verbs:
~RU changes to ~nakatta (it's like taking the ~nai ending and replacing the I with ~katta)
taberu -> tabenakatta (I didn't eat)
miru -> minakatta (I didn't see)
etc

U verbs:
~U changes to ~anakatta
oyogu -> oyoganakatta (I didn't swim)
hanasu -> hanasanakatta (we didn't talk)

Verbs ending in ~tsu are special: the ~tsu changes to ~ta, and then ~nakatta is added.
matsu -> matanakatta (she didn't wait)

Verbs with a vowel before the U are also special: the ~U changes to ~wa, and then ~nakatta is added.
au -> awanakatta (we didn't meet)

(I think I briefly touched those patterns for the present tense negative.)

And the irregular verbs:
suru -> shinakatta
kuru -> konakatta
aru -> nakatta
desu -> ja nakatta
(I don't think I mentioned - aru's present tense negative form is just 'nai'.)

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And I don't know if you know the difference between aru and iru?
They both mean 'to exist/there is' AND 'to have'.
But 'aru' refers to inanimate objects, while 'iru' refers to animate objects.

O-kane ga aru = I have money / There's (some) money
Inu ga iru = I have a dog / There's a dog

Again, it can change depending on context. Usually when iru/aru is referring to existence, it will be apparent:

Asoko ni inu ga iru = There's a dog over there

Annnnnd, so on. :D

0.o That's confusing! But I think you explained past tense for japanese better than my German teacher did for german past tense XD
And I was going to ask you what the difference was between aru and iru! So thanks for explaining that too ^_^
Is there a future tense in japanese too?

No, no future tense. It's usually determined by other words in the sentence... obvious time words like 'tomorrow' or 'next year', or words like 'tsumori' ("I intend to..."). The verbs generally just remain in their present form, either formal or informal.

oh ok. I have another question. what do I do about translating verbs like 'ryouri suru'? I mean, what do I do with the suru in the sentence?

Many verbs are created by taking a noun and adding 'suru' to the end. I wouldn't go hogwild trying to make up verbs like this on your own, but there are a lot that already exist in Japanese. By itself, 'suru' essentially means 'to do', although if you look in any dictionary it has about 50 other meanings. So combining it with a noun is like saying 'to do [noun]', making it into a verb.

So 'ryouri' = 'cooking/cuisine'
'ryouri suru' = 'to cook'

You should beware of some dictionaries, especially online ones, because they won't list the verb as 'ryouri suru'. They'll just list the word 'ryouri' and give you the noun definition for it, but also note something like vs or verb-s next to it. This way, you're supposed to know you can add 'suru' to the end, and should be able to figure out its verb form from there.

So how would I say it in a sentence though? Watashi wa ryouri o suru?

No, when 'suru' is attached, it's considered one word. It's just usually written with a space for ease of reading, I guess.

Watashi wa ryouri suru = I cook
Watashi wa tamago o ryouri suru = I cook eggs

Although, there are some 'suru' verbs/phrases that are used with 'o' in the middle. However, the use of 'o' twice in the sentence usually won't happen. For instance:

yume o miru = to have a dream
Konya yume o mita = I had a dream last night
Konya tamago no yume o mita = I had a dream about eggs last night

Etc *w*

Oh ok. Thanks

Ok, I have another question. What would I do if I have more than one verb in the sentence? Like "I went (or am going) swimming and skating today. Would I just connect the verbs with to or ya (depending on how much I'm doing)?

Verbs connect in the sense of "and" with their ~te form.
The ~te form is created by putting the verb into its informal past positive form, and then changing the final ~a to ~e. This does not mean that the verb is in past tense; it just happens to be how it conjugates.

Taberu -> tabeta -> tabete
Au -> atta -> atte
Oyogu -> oyoida -> oyoide
Hanasu -> hanashita -> hanashite
(And so on)

So you can write:

I sing (utau) and dance (odoru).
Watashi wa utatte odoru.

The final verb in the sentence will determine politeness and tense.

I went swimming and skating (sukeeto suru) today.
Kyou watashi wa oyoide sukeeto shimashita.

...Actually, technically, a more appropriate translation for your sentence would follow a different grammar pattern for 'going to do something' or 'coming to do something':

[Masu base verb] ni iku/kuru.
The ~masu base of a verb is what's left of the verb if you were to put it into ~masu form, but hack the ~masu off.
Taberu -> tabemasu -> tabe (masu base)

So:

I went swimming and skating today.
Kyou watashi wa oyoide sukeeto shi ni itta.

I'm going swimming and skating today.
Kyou watashi wa oyoide sukeeto shi ni ikimasu.

But, yeah, I'm getting off topic again. The problem is that we've barely touched the surface of grammar patterns... I could ramble on for a while about how ~te combines with other words to make lots of patterns too. But it depends on what you want to know, or what you feel you need to know.

Well, I'd like to have an idea of how to form sentences by the time my Japanese sister gets here but I'm watching anime and listening to jrock in Japanese so I think that's helping me understand what I need in a sentence and don't need.
Like, in english you'd say "she's very annoying" but in japanese you could say she is annoying" and then add an emphasing particle on the end right?
Also, just for a good idea about adjectives, for the most part you add -ku to the end right? (after making some slight adjustments)

Well, yeah, I guess to some extent the end-of-sentence particles can add in words that we'd normally say in English. But they're mostly there for feeling or emphasis (and be careful which ones you use when; some are male-only and you might get weird looks for using them). You don't need to be afraid to use 'very' (totemo) in Japanese.

Either would be correct:

"She's very annoying"
Kanojo wa meiwaku da yo!
Kanojo wa totemo meiwaku da.

Or for maximum emphasis, both words can be used: Kanojo wa totemo meiwaku da yo!

I'll start a thread for adjectives, because they have their own sets of rules.

Ok thanks so much for all your help. I mean, I got a book and CDs and dictionary but I've learned more than twice as much from you in half the amount of time. I'm also hoping sometime you could tell me about plurals too. Because I thought all you had to do was add -ra to the end of any word to make it plural but I'm not so sure now.

Np! I'm glad to help... I had no one to talk to when I started learning the language, and there were stupid little things my book never told me. So hopefully what I can teach you will help out.

Plurals are more on the uncommon side in Japanese. Once again, the speaker relies on context to determine whether the noun is plural or singular.

Risu ga iru = There's a squirrel / There's (some) squirrels

Usually surrounding words will make it obvious, like how future tense is determined:

Risu no gurentai ga iru = There's a gang of [punk] squirrels

But it's not impossible to come across plural nouns. Most popularly (and on the polite side), you attach ~tachi to the end of the noun. The suffix ~ra is more informal... and I can't be sure, but I want to say that ~ra is used more often when referring to people. Both suffixes can also be attached to pronouns or names with a slightly different meaning:

Watashi-tachi: us, we
Boku-ra: us, we (male informal)
Karin-tachi: Karin and the gang/group/friends (etc)

Ok thanks. I have something else to ask now. Actually, 2 things.
Prepositions don't change right? How they appear in the dictionary is how you would say them in a sentence? And also, I've noticed there's a lot of suru verbs since I've started practicing conjugating so I just want to make sure I'm doing it right.
"The girl with the red hair is annoying me."
Onnanoko ga aru akai kaminoke watashi o ira-ira shimasu (or shimashita in past tense)
Is that the right translation?

wouldn't it be something like:
"akai kaminoke no onnanoko wa watashi wo ira-ira shite imasu"
?