To remove old knobs or handles and replace them, loosen the screw on the back of the door that holds the old hardware in place, then remove the knob or handle.

To simplify placement of the holes for the new handle, check your home improvement store for a template that serves as a guideline for lining up standard holes at the side or bottom of the door.

Mark and pre-drill your holes carefully.

Before putting your new handle in place, fill any holes left by old hardware with wood putty, and paint that area.
Attach the new handles with screws.