Position the lock against a closed door and mark the screw holes with a pencil. Make sure that one part of the lock is on each part of the door and that they line up correctly.
Drill the pilot holes as marked with a power drill. The pilot holes should be one size smaller than the screw you are using.
Place the lock back into position and screw it in place.
Test out the lock by unlocking and re-locking the door.