what?? 10000?? how can people of japan remember of them?? is all of the kanji is used for the communicating?

There are as many as a million words in English. Do you know them all? Does anyone know them all? No.

Number of Words in the English Language

On the other hand, the average speaker only knows 10,000 to 20,000.

Interview with Ultimate Vocabulary

In other words, the average English speaker only knows possibly one or two percent of all words in the English language!

Just a tip for you: In the future, when you have questions about the language as a language (as opposed to the grammar or vocabulary), just think about your own native language. Often, analogies provide illumination!

ah ok so learnng kanji woun't be easy to study on my own i need some one to teach me so thats how difficult kanji is hmmmmm

How can somebody TEACH you KANJI? o_0

The only thing that helps here is your patience, will & hard work.
All you need is a book where:
1/ should be the order of strokes (otherwise, you won't be able to write them correctly)
2/ should be kun & on readings (knowledge of only visual form of kanji won't help you to read the word)
3/ should be examples of words with this kanji (you'll remember reading easier that way)

So, you take such a book and...learn kanji every day, practice writing, brush up the older ones so as not to forget them. You better not learn 20-30 a day. First that can be 3-5, but practice them till the positive result. If it's easy for you, take more. Less quantity= better quality. If you learn even 3 a day, it becomes 90 a month. ^_~

I've learned hundreds of kanji in a few months all on my own.