from console you would use
apt-get install gaim thats it
apt will search for gaim and install, you don't need to d/l yourself beforehand I would suggest getting synaptic, it the gui for apt...NICE!!!!!
This is what Synaptic looks like if your doubtful
I don't want to give you a link to d/l it because I'm not sure which distro you using and don't want to screw you up more, posting that with you user info will allow better responses to you questions..good luck