When deciding the handing of your door for the purposes of a door lock, it is not the same as when a carpenter is hanging the door. For the purposes of a door lock, you need to stand outside your garage and look forwards at the door. If the hinges are on the right of the door, it is a right handed door. For this garage door, you will need a right-handed lock.
If the hinges are on the left of the door, it is a left-handed garage door and you will need a left-handed lock.