Watashi wa usagi des'. = I am a rabbit.
Sono neko wa nyanki des'. = That cat is a "Nyanki". (The Pizza Cats are called "Nyanki" in Japan)
Kore wa konpyuta des'. = This is a computer
Sore wa pasokon des' ka? = That is a personal computer?
Hai, pasokon des'. = Yes, it is a personal computer.
Baka des'. = It's stupid.
"Ga" is very similar to "Wa". It marks the subject of the sentence. Sometimes it's hard to know the difference between "wa" and "ga". Sometimes they can be used interchangeably and still mean pretty much the same thing. "Ga" is used to link the word or phrase that precedes it to the adjective or verb that immediately follows it. It is a bit difficult to get the hang of. The best way to learn it is to see/hear how it is used, and eventually you'll catch on. So, let's try some examples. "Neko wa shippo ga nagai des'." (Neh-ko wah sheep-po gah nah-gai des). The topic is Cat = "Neko", marked as the topic by "wa". The subject is "shippo" = "tail", marked as the subject by the "ga" particle. Finally we have an adjective (that's a word that describes, in case you weren't paying attention in school); "Nagai" = "Long", and "desu" (des') ="is/it is". So: "Cat wa tail ga long is." or, "The cat has a long tail." "Watashi wa sushi ga suki des'."(Wah-tah-shee wah sue-shee gah sue-kee des) is "I like sushi." ("Suki" = "like") Japanese often leave off personal pronouns, like "I", "You", etc., so it would also work if I said "Sushi ga suki des'." as long as everyone already knows the topic; "Watashi". If I were talking about my friend, Omitsu, and I wanted to say that she likes tea, I could say "O-cha ga suki des'." (Oh-chah gah sue-kee des). The topic, Omitsu, is already known, be cause we were already talking about her. If we weren't, and I just felt like telling you "Omitsu likes tea.", I'd say "Omitsu-san wa o-cha ga suki des'.", so that you would know who/what topic I'm talking about. Do you get it now? If you do, I'm impressed, took me months to get "wa" and "ga"... Anyway, there's a few other ways these particles are used sometimes, but don't worry about that just yet, these are the basic uses that you are most likely to run into. Let's review:
Kore wa nan des' ka? = What is this? (This, what is it?)
Kore ga pasokon des' = This is a personal computer.
Watashi wa o-cha ga suki des' = I like tea.
O-cha ga suki des' = (I) like tea.
If you're still confused, don't worry, just pay attention to these particles when they come up in future lessons, and when your watching your favorite animes in Japanese (subtitled anime videos are great for helping you learn Japanese. How often can "doing homework" be that enjoyable?). You just have to know what to listen for.
*Note: For those of you also interested in reading/writing in Japanese, it's pronounced "wa" but written with the hiragana "ha". The "Cha" sound is made by combining the "Ti" hiragana (which normally sounds like "chi") and a small "ya".