actually, I want to improve my number theory concepts more and more as i need it in much extent. is there any good website or any book which can help me so as to make my needs? i am not weak or something like that in number theory, but still i wana improve it as much as i can till this year ends. thanks for any help in advance.

I do not know exactly what you are after, but generally Compute Science needs more like introduced in book

Concrete Mathematics
by Graham, Knuth and Patashnik

I have not been able to read it yet much but I have it, and the auctority of Knuth can not be denied.

Elementary number theory by David M Burton is a classic. Perfect for beginners and mid level.

If you have concept on Group theory, ring theory, Integral domain ( Basic abstract algebra ), then you should go for another classic, An Introduction to the Theory of Numbers by Niven, Zuckerman, Montgomery.

There are many classic books on number theory, but they basically has abstract algebra exposition, not recommended if you don't have any concept abstract algebra.

If you want to try number theory without abstract algebra exposition, then best is to practice problems from IMO ( International Mathematics Olympiad ) or any other mathematics olympiad question paper. You can find these type of questions in any olympiad training book for example Number theory by Titu Andreescu. Also you may google for more such questions.

You may go though these pdf's.