ok first of all, what distribution are you using? you may have mentioned it already but i don't see it. if you're using redhat/fedora, you can use up2date like Dummy-in-Linux said to update software on your system pretty easily (except of course up2date crashes a lot).
just look around on the main menu for "system" or "tools" or something till you see an updater, and it's pretty much self explanatory.
now if you're using a different distro, that's a different story so i can't answer your questions until you tell me the distro you're using.
btw, why do you need to update gaim so badly? you already have it installed, right?