Inspect the set of shower door handles to determine which handle is to be installed on the outer surface of the door. The inner handle typically has one or two screw holes, while the outer handle has a smooth finish.
Position the outer handle on the outside of the shower door, aligning its screw hole(s) to the hole(s) drilled in the glass door. Use a piece of masking tape, 8 to 10 inches long, to temporarily hold the outer handle in place.
Position the inner handle on the inside of the shower door, aligning its screw hole(s) to the hole(s) drilled in the glass door. Pass the tip of the screw, included in the shower-handle kit, through the screw hole in the inner shower handle. Use a screwdriver to tighten the screw. Do not over tighten the screw, as this can cause the glass to break. If the handle has multiple screws, install these in the same manner.