I know I'm coming to this thread far too late. Apologies.
But, picking up on the discussion above about where best to get information on learning the GIMP, I have no hesitation in suggesting that the best resource is 'Meet the GIMP'.
This link is to the older video tutorials and though we're onto much newer version so the GIMP, what's in those will give you an excellent basic grounding. It was this resource that brought me from the stage of 'Doh, what's post-processing?' (I mean that) to where I am now in terms of knowledge and, I hope, skill'.
Rolf, who's site it is and who's produced the tutorials suggests that a beginner should approach the videos in the following order:
001
066
037
025
003
004
005
009
010