Put the bicycle in a work stand or upside down on its handlebars and seat so that the rear wheel is elevated off the ground.
Use a combination wrench, usually 15 mm in size, to loosen the axle nuts of the rear wheel and remove it from the frame. Let the air out of the tire and remove the tire, tube and rim strip from the wheel.
Set the rim strip in place on the new rim, lining up the rim strip hole with the rim's valve hole. Set one tire bead on the rim and push the tube inside. Push the second bead of the tire up onto the rim and air up the tube to the pressure rating printed on the tire sidewall.
Slide the new coaster brake wheel into the dropouts of the frame. Put the chain around the coaster wheel sprocket and pull the wheel backward in the drop-outs to add tension to the chain. Tighten the axle nuts of the wheel with a combination wrench to set the wheel in place. It may be helpful to have a friend hold the wheel while you tighten.
Rotate the coaster arm (found on the left side of the wheel hub) until it sits just below the left chain-stay of the bicycle frame. Use the chain-stay bracket and screw to fasten the arm to the chain-stay of the frame. This arm is essentially what makes the coaster brake work, so be sure this bracket is tight and secure.
Take the bike out for a test ride. To stop, simply push backward on the pedals and the rear wheel will stop spinning.