I am completely confused!

Ok. We just got a new MacBook. I currently have a Mac Mini running 10.4.11. I also bought an Airport Extreme for my wireless. I have a Belkin ethernet cable from the Apple store. I can't figure out what to do first. My cable modem only has one port for a cable. The cable that is currently plugged into it runs from the mini into the modem. Even if I want to use the macbook just with the ethernet cable, I can't have the mini and 'book connected at the same time. I tried installing the AirPort Extreme disk on my mini and it wasn't compatible for some reason...help, I'm totally mixed up here!
Thank you!!

I think I need to have a wireless service hooked up through my cable provider.....maybe that's the problem

Sounds like you've got the right pieces, but they're in the wrong order. Typically the single cable out of the modem connects to the your Airport Extreme. Then the Extreme would connect to the Mini via cable and the MacBook wirelessly...

I still don't get it. I have a yellow cable that runs from the modem to the Mini, and now I have a black Belkin ethernet cable. My modem does not have slots for both to used at the same time.....according to Time Warner Cable they have to have a technician come out and install a wireless router for $49.00. Does this sound right?
Thanks again..

Don't hand over the $50.00 quite yet. The setup isn't really that difficult. Sometimes a picture is worth a thousand words. Here is a brief video of the setup. Video: Apple Airport Extreme explained - Soa - Video-Apple-Airport-Extreme-explained - AppleSource The ethernet wire from your modem will go into the wan port (circular icon that looks like the sun. Your Mac will plug into one of the other ports.

Once you are done with the physical connections here is an overview of the software setup. Woopid Video Tutorials - Configure a New AirPort Extreme/Time Capsule