7. You really only need 1 or 2 pin nails on each end if your using the construction adhesive. I promise, after it sucks the boards down and dries, it isn't going anywhere.
8. To finish off the edges, rip down the board to the width you need, make your cuts, glue, nail and enjoy!
**you don't need to miter the corners of your finished edge but it does look a little nicer**
If you want to or have to use new wood, here is a stain color and technique I like if your looking for an aged, graywash, barn wood look. I did it a few years ago on some shelves I made for my son's room and the tutorial is HERE.