We have WIFI in the house. My computer is supposedly WIRELESS. So I bought a wireless adaptor and plugged it in to the USB port, but I can't get online. Shouldn't I be able to with this computer?
Yes.
Travel to Control Panel/Network and set up the card so it sees both your machine and the Network/What specifically should I do once I get there?

I did go into device manager, where I noticed that there is a question mark next to the USB port, which I clicked on, and it then SAID a driver was not installed. When I clicked install driver (or search for driver, not sure), after a few moments of searching it said the proper driver was already in use.

I have been able to use this computer to get online before, but I had a card that slipped into the body of the computer itself, and then I plugged the cable that goes to the router into the card. But my housemates and I DECIDED to go wireless, so I needed an adaptor, and bought the item in this auction, which said it would get me online:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=310101254355&ssPageName=STRK:MEWN:IT&ih=021
But I have not been able to get on.
Did it come with a Driver CD ? ?
It could also be DOA.
Any lights on it to show it is on ?

Very hard to tell from your link since there are many items on that page.It did not come with a CD.

And the item for sale in that auction is the wireless adaptor. Check the title and the picture in the auction itself, not the ADS at the top.
Adaptor does have a light on some of the time when I plug it in.
It more than likely needs drivers installed...travel to the manuf. site and check out the SUPPORT sectionQuote from: patio on November 25, 2008, 02:49:17 PM

It more than likely needs drivers installed...travel to the manuf. site and check out the Support section