Instructions
Power on the Xbox 360.
Press and hold the Xbox guide button located on the center of the game controller until a light appears. It is a large button with a "X" decal design built into it.
Press the connect button on the Xbox 360. The connect button is a small button located underneath the power button on the face of the Xbox 360.
Press the connect button on the Xbox controller. The connect button is a small button located on the top of the Xbox controller.
Press the Xbox guide button on the game controller.
Choose the gamertag you want associated with that controller.
Insert "Halo 3: ODST" into the Xbox 360 disc drive, then launch the game.
Launch "Firefight" mode. The controller will be automatically signed in.