If your school uses standard DHCP, there's not much configuring to do. Open the Network pane in System Preferences and make sure the Airport Card is set up properly for DHCP.
When in doubt, there's usually a ton of tech types hanging around the computer labs in colleges. The ones at the university I go to are wonderful -- sometimes they'll look at you funny when you mention you use a Macintosh, but simply asking them for the setup information usually works.