To remove the old belt simply rotate the tensioner pulley with with a socket grabbing the center bolt on the tensioner. Slip the belt off the closest pulley and slowly release tension from the tensioner. Remove the belt from the tensioner and all other pulleys.
Be sure to check all of the pulleys and make sure they are clean and not damaged. Route the belt according to the diagram above leaving the tensioner for last. Rotate the tensioner and slip the belt on.
Be sure to double check every pulley before starting your vehicle.