Things You'll Need
Instructions
Turn on one of the computers that is connected to your wireless network and click on the "Start" button on the bottom tool bar. Click on the "Control Panel" and then choose the option that either says "Networking" or "Network and Sharing Center," depending on which version of Microsoft Windows you are using.
Make a copy of the name of the wireless network setup between your computers.
Plug the wireless network adapter into the USB port on the top end of the back side of the XBOX 360 console.
Push the green and silver "X" button at the center of the controller and then immediately let go of it to bring up the main menu. Navigate over to the "Settings" menu on the right side and then choose the option that says "System Settings." Highlight the "Network Settings" button and then press "A" on the controller. Choose the option to edit the settings and then type the name of your wireless network into the "SSID" field.
Backup through the menus until you are back in the main controller menu that has several different tabs. Press the blue "X" button on the right side of the controller to bring up the login menu and then choose the account that is signed up for XBOX live to sign in.