JapaneseGirl wrote:Hiragana and katakana have different sounds?
They represent the same sounds. kana represent all the sounds in Japanese (traditionaly 50) which is very useful. If you can hear the sounds you can spell a word. (unlike with the 26 letters of the roman alphabet)
For example ロ and ろ both represent the sound "ro" in katakana and hiragana respectively.
You could think of them as being like lowercase and capitals in English. r and R look different but represent the same sound. (kana are used differently however)
hiragana would be the main one. Characterised by it's rounded shapes it's mainly used for verb endings and particles etc. all the things that the imported kanji can't do on their own. But as they represent sound it is possible just to use hiragana. Although I think this is very difficult to read.
katakana, characterised by it's more angular shapes, tends to be used for loan words and also for emphasis and oddly (since the character shapes all seem very similar to me! ) for clarity.
Kanji on the other hand do not represent sounds as such but ideas.
Why there are so many of them and why it can be hard to master their readings.
木 is tree for instance, but it can be read as ki or moku or boku or ko depending on context! But regardless of this whenever you see 木 it'll have something to do with trees and wood.
Also many kanji are read with the same sounds. for example hashi can be bridge and chopsticks. but one is 橋 and the other is 箸
It can all be overwhelming when you're starting out.
Usually people learn hiragana first. It'll take a week to a month maybe. (search the forums for book or software suggestions)
Then you learn katakana, maybe half the time.
Then kanji, a long time and lots of effort unfortunately.
It's years of work to learn all 1946 of the jouyou kanji which would be the equivalent literacy level as a high school graduate. That said you don't need them all to start using them. And some people say you can do a lot with a core of about 500 kanji.
You can get by with romaji, just using the roman alphabet to represent the sounds, when you're starting out. But kana is much more useful in the long run.
Oh and welcome to the forums, feel free to ask any questions you like!
ganbatte ne!