If you're using RedHat and have installed all necessary packages ( lpr, printtool, and probably ghostscript), you can run a program called printtool, which will take care of setting everything up for you. (Notes: printtool needs to be run as root and under X. ghostscript is not installed by default, so you will need to install it yourself if you do not have a PostScript printer.)
In order to be able to print to your printer from other workstations, you have to follow a more complicated procedure which includes getting a Hesiod entry for your printer. If you want to do this, please ask on net-help@mit.edu and somebody will fill you in on the details.