My dad had a kind-of old Windows Xp-Pro computer. He got a laptop and gave the Desktop to me to put it in my room. The computer was connected to the internet for a long time, and I think it was plugged DIRECTLY into the phone jack. (With ONE of those special thing-es to alow the internet and phone to be used at the same time.) There is a Phone jack in my room, aswell as three standerd plugs. Also in my room is the internet router/modem, (Whatever you call it.) it plugs into the phone jack. There is also a wireless modem/router (Again, whatever you call it) that produces a internet connection that the laptop and MOBILE devices connect to. I also have the Ethernet (yellow) cable, and some cable with male USB on one end and female USB on the other end. (Yes, im 13 and I know what male and female USB is. DEAL WITH IT. ) But I think that cable was meant for the printer anyway. I have tried just about everthing, and I don't know how to connect this "device" to my computer via one of these cables. If more information is needed, thats ok.
Can anyone help? Is it GOING to be wired or wireless? I think since its a desktop, you would need the RJ-45 or the ethernet cable to be put in directly to your router and the other one at the back of your desktop. Otherwise, call your dad.

:PI will provide more info!
I have a SpeedStream 6520 wireless ADSL gateway from SIEMENS (Thats what it says on back) My computer is a Compaq.
XP-PRO.does you internet service PROVIDER use DSL?