Assemble the handles, if needed, by placing soft washers (provided in the handle kit) on the ends of the shanks or stems of each handle. Some handle kits do not use washers; on others, the washers are preinstalled. Inspect the handles to determine which is the outer handle. The outer handle is typically smooth, without installation screw holes.
Tear off a piece of masking tape from the roll, about 12 inches long. Position the outer handle on the outer surface of the glass, aligning its shanks or stems with the installation holes in the shower door. Tape the handle in place to prevent it from shifting as you align the inner handle.
Position the inner handle on the inner surface of the glass, aligning its shanks or stems with the installation holes in the shower door and the shanks or stems of the outer handle. Insert a screw in one hole in the inner handle. Turn the screw clockwise with a screwdriver until it holds the inner and outer handles together. Repeat to install screws in the remaining screw holes. Tighten the screws evenly, but be careful to avoid overtightening. Remove the masking tape from the shower door.