Choose a lock appropriate for your door material. Metal door lock kits will include metal-tapping screws. If you need metal-tapping screws but bought a lock made for wood, take the mounting screws into a hardware store and purchase metal-tapping ones in the same size.
Tape the lock installation template to the door and the frame. Press a pencil through the paper carefully and mark the exact location for each mounting screw.
Pull the trim off the top of the lock and line the mounting holes up with the marks. Screw the mounting screws through each hole, then repeat the process to mount the strike plate on the door trim.
Place the trim cover over the top of the lock and secure it with the trim screws.