Make sure you have read the legal bit on my home page.
Japanese is a peculiar hybrid language. Like European languages, it has grammar, with subjects, direct and indirect objects, nouns modified by adjectives, transitive and intransitive verbs modified by adverbs, and so on (if you are European and do not know what these terms mean, I strongly suggest that you learn to speak your own language properly before trying to learn Japanese). Like Asian languages, it is a topic-description language: you first set the topic of the conversation, and then talk about it.
The Japanese make a tremendous fuss about particles. Actually, they are no big deal. If you know any Latin, the similarity between Latin case endings and Japanese particles soon becomes obvious.
The Japanese also make a tremendous fuss about levels of politeness. This is largely irrelevant. Except where I specifically note otherwise, the sentence patterns I give here use the level of politeness commonly used by foreigners in Japan (whether speaking to Japanese people or to one another).
So here is some Japanese:
saburinasanhaoshyaberidesu. "Sabrina is a talkative person." desu is an audible equals sign; it also sets the politeness level; it is not really a verb, but does quite good verb impressions. The particle pronounced "wa" denotes the topic (in this case, Sabrina); in hiragana this particle is written ha; don't ask why, just get used to it.
The pattern here is NOUNhaNOUNdesu. The pattern can also be used for adjectives: NOUNhaADJdesu. For example:
saburinasanhaurusaidesu. "Sabrina is noisy."
saburinasanhakireidesu. "Sabrina is pretty."
Once the topic has been established, it need not be repeated. For example:
saburinasanhaoshyaberidesu.urusaidesu. "Sabrina is a talkative person. She is annoying."
If you change the topic but say the same thing about the new topic as you were saying about the previous one, change ha to mo ("also"):
saburinasanhaurusaidesu.warumonomourusaidesu. "Sabrina is noisy. The ruffian is also noisy/The ruffians are also noisy." Note the lack of change between singular and plural. One ruffian or several, it's all the same in Japanese.
This is the only simple sentence pattern in Japanese. Make the most of it. From now on, things get difficult.
This is easy too, so we might as well deal with it here.
To make a statement into a question, add ka to the end. For example:
saburinasanhaoshyaberidesuka. "Is Sabrina a talkative person?"
Appropriate answers are hai (yes), ee (yes, but rather less formal) and iie (no).
To make a statement into a rhetorical question inviting agreement, add ne to the end. For example:
saburinasanhaurusaidesune. "Sabrina is noisy, isn't she?"
hai, ee and iie are all possible answers, as before, but the most common answer is ne, which is a form of rhetorical agreement (here meaning "yes, isn't she?").
To add emphasis to a statement to indicate strong personal opinion, add yo to the end. For example:
saburinasanhakireidesuyo. "Sabrina really is pretty!"
There are many other things which can be added to the end of sentences, but these three will do for the time being.
In general, replace desu by jyaarimasen. For example:
mahoutsukaisamahaoshyaberijyaarimasen. "The wizard is not a talkative person."
mahoutsukaisamahakireijyaarimasen. "The wizard is not pretty."
But (I said things were going to get difficult) i adjectives are different. Change the final i to kunai and don't change desu.
mahoutsukaisamahaurusakunaidesu. "The wizard is not noisy."
jya is an informal contraction of deha (pronounced "dewa").
The following two sentences are identical in meaning, but the second is slightly more formal.
mahoutsukaisamahaoshyaberijyaarimasen,
mahoutsukaisamahaoshyaberidehaarimasen.
(Health warning: what follows is unofficial)
If you want a quick way of negating nouns and na-adjectives,
add ganai and don't change desu.
The result, after adding ganai, is grammatically an i-adjective.
mahoutsukaisamahakireiganaidesu. "The wizard is not pretty."
mahoutsukaisamahaoshyaberiganaidesu. "The wizard is not a talkative person."
If you are learning Japanese to talk to Japanese people, you can use ganai in this way and be understood. However, it is not in the books, so if you are learning Japanese to pass an exam, don't use it.
Japanese doesn't have a future tense as such. The "present tense" covers both the present and the future. But it does have a past tense. In general, replace desu by deshita.
saburinasanhaoshyaberideshita. "Sabrina was a talkative person."
saburinasanhakireideshita. "Sabrina was pretty."
As before, i adjectives are different. Change the final i to ka,ta and don't change desu.
saburinasanhaurusaka,tadesu. "Sabrina was noisy."
In general, replace desu by jyaarimasendeshita. For example:
mahoutsukaisamahaoshyaberijyaarimasendeshita. "The wizard was not a talkative person."
mahoutsukaisamahakireijyaarimasendeshita. "The wizard was not pretty."
You can guess what's going to happen with i adjectives, can't you? Change the final i to kunaka,ta and don't change desu.
mahoutsukaisamahaurusakunaka,tadesu. "The wizard was not noisy."
And, just to make things a little more difficult, there's a more complex pattern used when only part of the sentence is negated.
watashihatata,tanjyaarimasen. "I didn't cast a spell." Someone cast a spell, but it wasn't me (oddly enough, it was the wizard). This is a variant of the ndesu pattern.
As before, jya is an informal contraction of deha.
As I said earlier, the particle ha denotes the topic. So what if you want to say something without changing the topic?
This is surprisingly easy to do. Replace ha by ga. ga denotes the grammatical subject of a clause without changing the topic.
shyokudouhasaburinasangaurusaka,tadesu.mahoutsukaisamagaureshikunaka,tadesu. "In the dining room, Sabrina was irritating. The wizard was unhappy." The topic of conversation remains the dining room and events therein, not Sabrina or the wizard.