New Airport user, base station question

Okay, I just recently picked up an Apple Base Station. I have a PowerMac G5 and an iMac G5 that I’m trying to network, but I’ve run into a problem. I thought I had hooked my Base Station up correctly, but apparently I didn’t. My computers recognize that the base station is there, but I cannot get any internet access through it. I know I’m probably just making some dumb mistake along the way, but does anyone have any ideas?

Also, both the Mac’s obviously have Airport cards.

I'll take a stab at your problem. When that happens to me, but with a different router, I usually have to unplug everything, cords and cables from the modem and reset everything for me to get back my internet.

I don't have apple's airport extreme base station but when I hooked up my router
(dlink) I made sure all firewalls were off until I was getting an internet connection.
The dlink has its own firewall, my powerbook it's own, and my pc. Then like iwhat said a factory hard reset.