Linux is a Freeware version of a Unix type system. It operates just like any pother v ersion of a Unix operating system.
Best way to find out stuff on it is to go to google www.google.com/
and ask for Linux and something like Basic
you'll get all sorts of help.
I would suggest that you use Mandrake 9 as your first attempt to load a machine its the easiest of all on installing.
In fact its probably easier than most windows installs at least in most cases.
To get a copy you can download the stuff ( only if you have broadband. You can also get Cd's from Mandrake
or for cheap guys try EBay.