Welcome to SDD Pilot210e. First you will need to tell us what you are driving/working on. Go to the Users CP and fill out your signature. This will help us help you. Good Luck.
pull up on the belt and you will feel the belt release upwards, when you pull the belt up, there is a locking mechanizm on the underside of the belt tensioner, kinda hard to get to (especially at night, like when i had to change my alt.) lock the tensioner into place, and the belt will now have slack in it.