Instructions
Wireless Connection
Press the "Guide" button on the controller to load the Guide.
Select "Settings," and then select "System Settings."
Select "Network settings" and select the wireless network to which you want to connect. Enter the network's password, if prompted.
Wired Connections
Turn off both the Xbox console and your router or modem.
Connect one end of a LAN cable to the LAN port on the Xbox and the other end into an available LAN port on your router or modem.
Turn on the router or modem and wait for it to boot up.
Turn on the Xbox console.
Press the "Guide" button on the Xbox controller.
Select "Settings | System Settings | Network Settings | Wired Network."
Select "Test Xbox LIVE Connection" to verify that the Xbox is connected to the Internet.