Instructions
Measure the distance between the router and the Xbox 360, following the path that the Ethernet cord will use. Compare the length of your Ethernet cord against this measurement to verify that your cord is long enough to reach both devices. For easier rearrangement at a later time, use an Ethernet cord with a few extra feet of length.
Connect one end of your Ethernet cord to a LAN port on the router. Observe the port's number, if labeled on your router. Place the rest of the cord in its planned path, optionally tacking it behind wall trim with cable fasteners every couple of feet.
Connect the other end of the Ethernet cord to the RJ-45 port on the back of your Xbox 360. Power the Xbox 360 on. Look at the router's indicator lights to verify that the connection is working, if the router is equipped with this feature. Further test the connection by signing in to Xbox LIVE or by using the Internet on your Xbox 360.