Instructions
Choose a wireless network standard. The Xbox 360's network adapter conforms to all three wireless network standards--802.11a, 802.11b and 802.11g. The first may suit you best because 802.11a generally is less susceptible to interference from devices like cell phones and microwaves. You can set this standard from your base station (usually your desktop computer).
Attach the network adapter to the console. Press the tabs on the adapter into the two slots on the back of the Xbox 360. Then, connect the USB connector of the adapter to the USB port on the back of the console. Flip the antenna up, but do not try to swivel it on its axis because it is designed to only move parallel to the adapter.
Enter the "My Xbox" area of the Xbox 360 Dashboard, followed by "System Settings." Choose "Network Settings" and then "Configure Network."
Scan for your existing wireless network by entering the "Basic Settings" tab and choosing that option. Head to the "IP Settings" section where you can let your router automatically assign an IP address to your Xbox 360, per Microsoft's recommendations. Your console should now be connected.