Begin by removing the plastic shrouding around the base of the exercise bike with the screwdriver. This shrouding keeps clothes from getting caught in the belt and makes it difficult to access the belt unless it is removed.
Use the ratchet set to remove the axle nuts on either side of the rear wheel of the bike. Slide the wheel forward slightly so that you can slip the belt over the lip of the wheel. Now slide the wheel backward and out of the chainstays of the bicycle. Slip the belt off of the front sprocket and through the chainstay in the rear.
Install the new belt by sliding it over the front sprocket and through the chainstay. Slide the back wheel back into position and slip the belt over the lip of the wheel then firmly and evenly push the wheel back so that the wheel is straight and even. Tighten down the axle nuts, reinstall the plastic shrouding, and test the bike out.