Place an old towel in the bottom of the tub to prevent the porcelain or fiberglass surface from being scratched while you work.
The adapter kit comes with a diverter device that attaches to the shower stem and can direct the water in either of two directions (pictured). This enables you to use two showerheads from a single water source.
Remove the old showerhead using adjustable pliers. You may want to wrap the jaws of the pliers with tape to prevent them from marring the chrome. Using a rag (and, if necessary, some paint thinner) to remove any old plumber's putty or Teflon tape left on the threads of the shower stem.
With the old showerhead removed, you can attach the diverter. It's important to make sure that the supplied washer is placed in the neck of the diverter according to the directions that come with the kit (pictured).
Apply some new Teflon tape to the threads of the shower stem to help prevent water leakage (pictured). When applying Teflon tape, wrap it in the direction that the fixture will be tightened. If the tape is wrapped in the opposite direction, it may tear when the fixture is installed on the threads, and thus will be ineffective at preventing leaks.
With the Teflon tape applied, attach the diverter to the shower stem (pictured), and hand-tighten it. Carefully tighten the connection using a wrench if necessary, but avoid over tightening this (or any) plumbing fixture. Making certain that the appropriate washer is installed in the neck of the fixed showerhead, attach the head to one neck of the diverter and tighten it down.
With the showerhead installed, apply Teflon tape to the other neck of the diverter (pictured). Attach the hose-extender attachment – with the hand-held shower attachment – to the free neck of the diverter. An attachment that fastens to the shower stem holds the hand-held attachment when it's not in use, and allows it to be positioned as a secondary fixed head.