Yes...you have to loosen the alternator assembly...there will be a long adjusting bolt and a perpendicular bolt that holds it onto the alternator bracket. Loosen the perpendicular, short bolt, then the long adjusting bolt. Slide the head of the long bolt out of the bracket slot, and loosen any other bolts that would prevent the alternator from sliding forward in its bracket.
Then, you should be able to push/pull on the alternator and it will slide along little channels in its bracket. Slide the belt over the pulley, route it along its other pulleys, then pull the alternator back into place.
Slide the adjusting bolt back into its little slot, then tighten the perpendicular bolt so that it can't slide out of the slot. Then, while applying pressure with a screwdriver to the head of the adjusting bolt so that it doesn't slide out, tighten it until the belt is taut. Start the car, and if the belt is squealing (slipping), you need to tighten the adjusting bolt more.
Good luck...buy a Haynes manual for your car, it will be $15 well spent.