[GIMP] Removing White Backgrounds.

Can anyone enlighten me on how to remove the white background from pictures on gimp?
Conquer Club, a free online multiplayer variation of a popular world domination board game.
http://rzmhprwww.conquerclub.com/forum/
http://rzmhprwww.conquerclub.com/forum/viewtopic.php?f=649&t=120637
TheSaxlad wrote:Can anyone enlighten me on how to remove the white background from pictures on gimp?