On a regular baisis here at OStatic, we're committed to compiling documentation and guidance resources for popular open source platforms and applications. After all, one of the most common critcisms of open source creations is the lack of official project documentation. One of the best ongoing projects for producing free open source-related documentation is FLOSS Manuals. It's an ongoing and ambitious effort to build online guides for open source software. Recently, the site has added useful documentation for some projects that may interest you, including the great open source graphics editing application GIMP. Here is how to get the latest guides from FLOSS Manuals.
GIMP for Graphics. If you work with graphics, or if you want to start doing so, you may already use GIMP, one of the very best open source graphics applications, or you have it on your radar. GIMP is so powerful that it can be daunting for new users, and FLOSS Manuals has an excellent getting started guide available for it, here. Once you've mastered your GIMP basics, you can find even more guidance in the free online guide in Grokking the GIMP.