Use a pair of pliers to remove the staples or brads that are holding the thin back panel on the back of the bookcase.
Lay the panel down flat, and then choose some paper that compliments your room to cover that panel.
Depending upon the width of the bookcase you'll either want to run the paper across the width of each shelf in strips or if you have paper the same width as your bookcase you can run the paper vertically right down the panel.
Use some spray adhesive to adhere the paper to the backing.
A craft knife will make short work of removing any excess pieces from the edges.
Now all you have to do is reattach the back with some small brads or a staple gun. All you have to do is put your shelves back in place and you're all set.
I'm Mrs. Fixit and it's just that simple!