Oh sure, i thought that you all know how to use icon.png
So it's easy, You download CandyBar
http://www.panic.com/candybar/d/CandyBar%203.2.1.zipThen you Drag CandyBar in Application folder. You open CandyBar

clic on application folder(
Change application icons), then you'll see all your application icon. Open the zip file with all
customisated icons, and juste drag in candybar.
That is for Mac user
For PC i don't know how... you can search on google how chnage icon on "vista" or "seven"