Here’s what you do…
1.Buy a wireless adaptor from best buy or where ever you get your gaming supplies. Wireless adaptors run around $100 for the one I go at best buy. Heres a link to another good place to get them
http://www.thegamerush.com/details.php?products_id=101 .
2.Be sure to have a USB Flash Drive to setup your wireless connection.
3.Plug in your wireless adaptor into the back of your 360 and plug your USB Flash into the computer.
4.Start up your 360 with no game in the disc drive so it goes to the Xbox dashboard.
5.Then go to the last tab to the left (purple screen) and then select wireless connection then read the short description.
6.Go to the Xbox web site stated and follow the instructions given there and then download the wireless option onto your USB Flash drive (they may ask you at some point in time to connect you USB Flash to your modem).
7.Once your USB Drive has the wireless download on it plug it into the USB drive on your 360.
8.Your 360 might restart and then you should be ready to go.
Hope this helps…