Unbolt the brake caliper from the rear hub using the 3/8-inch ratchet and socket, then set it on top of a jack stand to support the caliper and keep the brake line from getting damaged. Be sure to keep the emergency brake cable straight to avoid twisting it out of shape.
Slide the rotor off of the hub using your hands and set it to the side to be recycled. Slide the replacement rotor onto the hub.
Bolt the caliper back onto the hub using the 3/8-inch ratchet and socket. Reinstall the rear tires using the tire iron then lower the vehicle using the jack.