Okay, I'm going to explain a little bit about this operation here. This is a nifty little tool that fits into your drill and it has a screwdriver tip on one end, and then if you just push it up like that, it flips over and has a counter sink on the other. Slide it back in. Push down and you might have to mess with it a little bit and make sure it stays in. There it is. Now what this end does, is it's going to cut a hole where the little hole in the middle of that that fits this screw. It cuts a hole like that. There's a hole in the center that's going to act as a guide later when we start to assemble the book case and it also forms a hole that fits the end of this screw so that when you put the screw in, this end fits snuggly into this shape that the counter sink cut.