Take one end of the Ethernet cable and plug it in the back of the XBox, the other end of the cable you have to plug on your computer. On your computer go to Start and then go to My Network Places, now select View Network Connections. Right-click the Wireless Network Connection, and go to Properties. Select Advanced tab on top of the window and make sure the two boxes are checked, press OK to continue. Now turn on your XBox and go to Test XBox Live. Wait until the test ends and then you will be able to connect to XBox Live.