Synaptic is the best way to install programs and should all ways check there
first. If you have your extra repositories enable. You'll even get more
programs to install. If you know the deb package you want to install. The easy
way is to open up the terminal and type in
sudo aptitude install (name of program)
Here is several link on you question too.

http://monkeyblog.org/ubuntu/installing/
http://psychocats.net/ubuntu/index