To lock the door from the outside to lock the slide lock from the outside you need to install a lock handle with the spindle inserted into the square hole next to the operating lever.
How to install garage door bolt lock.
In either case installing a deadbolt lock into your exterior garage door is probably the most cost effective way of increasing your residential security.
Make sure that the there s enough space for the bolt to pass through the rail and for the deadbolt to go on.
If money is an issue as these days it often times is you can perform the installation yourself.
Once installed turn the handle 90 degrees to lock the slide lock.
After you have drilled the holes fasten the lock in place with screws.