It's not really simple. The locks are single keyed, there is no master key: thus each pin is two pieces. This makes it fairly simple compared to mastered systems where each pin may be in many sections. However, you only have the pin sections that are in the lock and they won't make any new cut depths - you can flip a stack over and get a new cut there but you're very limited on what you can do.
To fit the lock to a key you have using the pins you have... it's unlikely you will have pins cut where you need them. What you do is find what pin cuts match cuts on your key and leave the rest of the pins out. This makes it easier to pick the lock and more likely that any random key that fits in the lock will turn it. You can also remove all the pins and make it a non-lock: anything - screwdriver, key, nail file - will turn it (although it looks like a lock and maybe nobody will try turning it).
