Couples' Devotional Bible (NIV) that I have been sharing from. I got it for about ten bucks on amazon. I wanted to dress it up a little bit (cuz that is what I like to do) with some pretty paper and ribbon. I also wanted to make it special, just for me and hubs.
First, if you want a ribbon bookmark(s), you need to measure it. Make sure it comes down past the bottom of the book... and then make it long enough to reach mid-spine for plenty of room to attach it with double sided tape (or sticky strip).
Then insert your book flap. I needed to use two pieces of paper to cover the whole thing, the back side is about 8 inches of paper. I attached the two pieces at the seam with a piece of sticky strip. Then insert the back flap and voila, you are done with the cover!