I have photoshop c4 can any1 give me some advice how to work in it,how to make textures,how to make in different sizes(128x128...).....

Don't use CS4, I assume you cracked it, and aren't really familiar with image editors.
Download gimp, it's easy, legal and free.

For tutorials: I strongly suggest checking these boards out:
Tutorials
Art
For the art board, if you see something you like, PM the creator and kindly ask for help.

Not sure to close this or not, I'll just leave it.

*edit: I'm not familiar with PS CS4, but when you open a blank file, you should be able to define the dimensions.
Be sure to put in pixels, not mm/cm...