I have a Dell Dimension 2400. Do you know if it has a wireless card?
The manual doesn't show one but all you have to do is look at the back for an antenna connection.
what does it look like?
Wireless would have been an option when you bought the computer.
Make sure all your devices are connected and powered on then
Click Start->Run, enter devmgmt.msc. Look under network adapters. Do you see a wireless adpater listed? Or just your LAN ethernet adapter?
Click Start->Run, enter: msinfo32. Click the + sign next to Components to expand it
Click Problem Devices. Anything appear?
If yes, click on it, Ctrl-A to select all, Ctrl-C to copy it, Ctrl-V to paste into next post
If nothing appeared here either you don't have a wireless card in your computer
Yes, if you don't remember specifying a wireless adapter when you bought the PC, then you don't have one.
An antenna connection is just a male threaded connection. If you aren't sure what a wireless card looks like, look one up at any online computer parts site.