Summary/Excerpts of (and not a substitute for) the Open Publication License:
The Open Publication works may be reproduced and distributed in whole or in part, in any medium physical or electronic, provided that the terms of this license are adhered to, and that this license or an incorporation of it by reference (with any options elected by the author(s) and/or publisher) is displayed in the reproduction.
The GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software suitable for such tasks as photo retouching, image composition and image authoring. This site contains the Gimp User's Manual which is the official and complete guide to Gimp. You will also find parts of the upcoming Gimp User's Tutorial; a book that will help you learn how to create great art in Gimp step by step.