How do you loosen alternator to change belt on a 1998 Pont?

Does your car have one belt? Or does it have 2 belts? if it has one's called a serpentine belt and you need to find the idler pulley and insert a 3/8 inch ratchet in the hole and take the tension off the belt, slide the belt off the pulley and then replace the alternator. With serpentine belts, you do not adjust the slack on the belt using the alternator, the idler pulley adjust the slack on the belt and keeps tension on it. If you have 2 belts then you may have an adjustable alternator but most cars this new have one belt. If you have 2, check back with your question updated.