Get a plain piece of printer paper and make two dotted lines on each end about an inch in from each side. Make the dotted lines go up about 3 quarters of the way. See picture below. This will be your pattern. Next, cut out your material around this paper. I added a little extra at the top to mine because I wanted it to be longer.
Then, fold back the front top portion and the back top portion to make a hole so a ribbon can go through it. Sew each flap down remembering to leave the space for the ribbon.