The Gimp is on Linux the reference software for image manipulation. In june 1999, I begin to use it. It seems very powerful, not simple also...
When the power of Linux comes on Windows...
(funny : a Mac Mac treated on Windows by a Linux software...)
In june 1999, the Windows version is a beta one. So be careful buy using it...
To download, go on the Win32 page of the Gimp site. Always on this site, you will fond a large documentation , particularly some tutorials to do the following images and others, click on it to reach the page :