its the one that goes to the AC, the Alternator, and the AC idler pulley and something else. I dont know how to take belt off and i need to replace the AC idler pulley... Also, i have already started screwing with stuff... uh oh.

 

Look here:
http://integra.vtec.net/geeser/megamax/60k_service.html
Be careful, I tightened mine because it was squeaking and a month later the alternator failed. My warranty covered it thankfully...