gimp-2.6.5.tar.bz2 (from gimp.org)
tar xvf gimp-2.6.5.tar.bz2 cd gimp-2.6.5 ./configure makesudo make install
gimp-2.6.5.tar.bz2 (from gimp.org)
tar xvf gimp-2.6.5.tar.bz2 cd gimp-2.6.5 ./configure makesudo make install
Some distros (debian, ubuntu, gentoo) also give you ways of doing it.
Actually for GIMP you're supposed to add some other magic in the ./configure step.
But for the sake of this demo I'll skip that for now.
But what if it doesn't build?