Downloading and installing programs follow fairly standard procedures. For good instructions on this, read:
In a nutshell, you'll have to download the source code for the program that you want, then unzip it. Once it's unzipped, you need to read the README file that comes with each program. In it you'll find information on everything from how to install the program to what other programs that are required to run the one you are about to install. VERY IMPORTANT!!
Just looking around the ID software site I didn't see anything for Quake on Linux. But I'm not a gamer so I don't know if there's anything else out there. All of the files I saw on the ID site all stated that the games needed to be run on Win or OS2 platforms.
-----------Edited to add the following:---------------
I stand corrected. Here's something right up your alley:
[Edited by billsabub on 03-25-2001 at 04:09 AM]