Hi! This is Jon on behalf of Expert Village. In this video clip, we will be installing our back piece. Once we've dry fit our back piece and made sure that it fit pretty snuggly, we need to remove that so that we can ready to glue it and pin nail it. The pin nails on the left here are the ones that I use when installing my trim. They are about an 1 1/4 long. However whenever I install my back piece, I don't need to go through as much material so I've got this much shorter pin nail. If you take a look at the back, I have this little gap here and when I pull my sides together, it closes. That tells me that one of my sides are just a little bit warped. A lot of times when you are using lumber in long lengths, here we have a 6 ft. long bookshelf, the board tends to warp or they could crown a little. We need to correct this when putting in our back piece so that when it is standing up on the wall it looks straight. First I am going to put a small amount of glue around my entire project on that rabbet. When I put the back piece on, it is going to secure to that glue and that is going to hold my project nice and square. Next we are going to position our back piece in place. After that I am going to place a clamp on the section that bows and just pull it in tight. Then I am going to put a few pin nails in to hold it in place. Now I am actually going to angle the gun into my lumber so that it doesn't show through on accident and we will go ahead and go around and put a few nails in.