go to http://www.jooneworld.com/.

btw, do u really understand/master neural network? do u mind if i
consult you about this? i am interested in this field but i have no
knowledged about this.

Well, I'm supposed to write a application (in Java) wich, by reading some
information from different monitoring hardware, predicts the disease of
patients in hospitals, knowing the diseases and symptoms they had in the
past. It's a future project, right now I'm stuck with another one, but I
want to learn before I go into it.
No, I only understood the basic cell, the neuron :)), it's quite an easy
one.

can give me some good sites on this?

There are some pretty good articles on neural networks here:

http://www.generation5.org/essays.shtml#nn

For those that know C++ (IIRC the OP does) there is also some source code.