If you look on the front of the 360, below the CD Tray, there is the black IR receiver window, then 2 memory slots (A and B), then a little round button with 3 little curved lines next to it.. that's the sync button
1. Make sure the controller is on, press and hold the back and start buttons until the green lights on the controller flash
2.Press the sync button on the console for a second or so, release
3.On the back of the controller, between LB and RB is the same round button, press that for a second or so, the controller green lights should flash, then only one light up when it's connected!..