Things You'll Need
Instructions
Turn on your computer and connect to the Internet through your air card.
Connect the ethernet cable to the computer, and the other end to the Xbox 360.
Access the "Control Panel" on your computer and enter "Network Connections." Once in the Network Connections screen, click the wireless network that represents your air card, then hold down the "Ctrl" key on your keyboard and click the network connection labeled "Local Area Connection."
Right-click either of the connections and select "Bridge network connection." This will enable your local area network connection to use the connection generated by the wireless air card.
Turn on your Xbox 360 and go to the "Settings" menu. From there, select "Test network connection," and the Xbox 360 will find and connect to the internet being provided to it via the bridged air card connection.