Found some more tutorials showing how to use the free open source image editing software GIMP. One is called Gimpguru.org and includes for example textual tutorials like how to remove red eyes in photos. The website is maintained by Eric R. Jeschke and though the last news post is from May 16 2006 and the front page is last modified May 17 2006 the tutorials seems adequate.
The other GIMP tutorials are interactive screen casting videos (think it’s produced with Camtasia) and in Swedish. The tutorials are produced by Håkan Källqvist, an art teacher and working for The National Resource Centre for Educational Media (swe. Multimediabyrån) at The Swedish National Agency for School Improvement (swe. Myndigheten för Skolutveckling). Thanks, Håkan!