I had one green book and I covered two in green. This is how I did it.
I cut the paper to just bigger than the books width. The paper that I had didn't cover the whole book (we'll see that later). I used 12"x12" paper. I folded the paper on one edge a little over an inch as below on one of the edges.
Use some tape on the inside of each edge. Tape it as it shows in the picture. Sticky side out.
Repeat on both sides and slide the book cover into the pocket it made.
Fold the paper around the book and tape on the back side. I used painter's tape so it could easily be removed without hurting the book.
I creased the edges to make it look like the real cover.
I used them to add some height to the the arrangement.
Do you decorate for St Patty's Day?
Here are a few projects we've done in past years.