This can be done one at a time or both at once, although you might run out of hands if you try that way.
- Turn the microphone on - you have to press and hold the power button until a green flashing light appears. If the green light keeps flashing on and off you have done this successfully. If there was a blue light for a split-second and then nothing, you didn't hold the power button down long enough. If nothing happens, try replacing the batteries. If the green light flashed for a while and then went off, you probably held the power button down for too long.
- Once you're sure the microphone is on, press and hold the power button again - this time don't let go. The flashing should speed up. When this happens, press the sync button on your xbox 360 (a small white button between the CD tray and the power button). The green flashing on the microphone should change to blue and then disappear. When this has happened, the microphone has sync-ed and you can repeat the process for the other one.
- Enjoy singing :)