Instructions
Connect the standard Xbox 360 controller to the Xbox 360. Unlike the other instruments used in "Rock Band 2," the "Rock Band 2" microphone can only be used if a regular Xbox 360 controller is connected.
Plug the "Rock Band 2" microphone's USB cable into a USB slot on the Xbox 360. There are two USB slots located on the front of the Xbox 360 and one on the back. Any of these slots will work with the "Rock Band 2" microphone.
Start the "Rock Band 2" game. If both the Xbox 360 controller and the "Rock Band 2" microphone were properly attached to the system, the game will display a black-and-white microphone image whenever you begin to load a song. This image means that the microphone is connected to the system and can be used to sing any of the songs available in the game.