You push a tab and a portion slides out. The piece that slides out looks like you would mount the staples and just slide it back in. But that isn't how it works. Instead, you simply place the staples {pointy side up} in the spot where the portion slid out. You slide the portion back in over the staples. I've attached a pic, that shows the staples in the correct spot. Hope this helped, this boggled me for a few days until I figured it out.