Turn off the water supply
Plug the drain
Remove the handle screw or cap
Pull off the old shower knob
Remove the escutcheon plate if needed
Unscrew and remove the valve stem adapter if needed
Compare the old knob and parts with the replacement
Install the new adapter or handle base if required
Slide the new shower knob into place
Tighten the set screw or retaining screw
Reattach the escutcheon plate if removed
Turn the water back on
Test the knob for proper operation and leaks