Japanese language is made of three japanese symbols.
Japanese symbols, Kanji is derived from chinese symbols. Japanese kanji symbols is same as chinese kanji symbols.
Hiragana is a japanese script to use words those are not there in kanji. Katakana is used to write foreign language words.
Most of the Japanese are written in hiragana. For whatever word there is Kanji available, it is used. Whenever there is some english word or a word derived from some other language than chinese, it is written in kanakata.
If you really want to learn japanese, we recommend that you have a look at learn janapese site. they have some good basis as well as intermediate and advanced japanese learning lessons.