How to use GIMP

GIMP is an acronym for GNU Image Manipulation Program. It can do photo retouching, image composition and image authoring. Use it as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, an image format converter, etc.

Introduction:
http://www.gimp.org/about/introduction.html.

Tutorials: http://www.gimp.org/tutorials/