"Chroma" Keying in Gimp
This is how you Chroma key AKA extract object out of a solid background (can be green, blue, red etc...)
I think Gimp is a fantastic project and even though I am a Photoshop user and find gimp very hard to use, I wan to create tutorials for gimp to show other people how powerful gimp is and how good open-source (free) projects are.
If you want to see more tutorials please comment.
You can download gimp from here
http://www.gimp.org/
Catch up with me on Twitter
https://twitter.com/#!/Studio76HD
Take a look at this page
http://digitalstudio7.blogspot.com/