The Bathtub Drain
Take out the stopper from the existing drain. You usually just need to pull or pry it out gently to remove it. Use a small putty knife if you need to pry it out.
Seal the lip of the new drain with plumber's putty.
Screw in the new drain by hand, then tighten it with a dumbbell wrench. Do not cross-thread the drain.
Wipe up any putty that has spilled onto the drain or tub; use a damp cloth.
Diverter and Spout
Determine if the spout is connected to the plumbing pipe by threads or if it slips on. Look at the underside of the spout. If there is a set screw, you have a slip-on spout. If there is not a set screw, the spout is screw-on.
Loosen the set screw with a hex wrench if you have a slip-on spout. Twist and pull the spout from the pipe protruding from the wall.
Slide the new spout on the pipe and tighten the set screw.
If you have a screw-on spout, turn it counterclockwise to remove it. If the new spout does not fit the pipe or if the threads on the pipe are corroded, you will have to replace the pipe.
Screw the new spout onto the existing pipe or the new pipe you have installed.
Grasp the nipple pipe that extends from the wall and attaches to the shower head; use a pair of channel locks. Place a rag between the teeth of the pliers and the nipple to protect the metal surface.
Use a second pair of channel locks to grip the shower head close to the threads. Place a rag between the pliers and the shower head.
Turn the channel locks counterclockwise to remove the shower head.
Wrap the threads of the new shower head with Teflon tape. Apply two layers clockwise.
Thread the new shower head onto the shower nipple, taking care not to cross-thread the head. Continue screwing the shower head onto the nipple using a rag and channel locks. Turn the shower head until you feel resistance.