I always used a zipper closure on mine. Make sure you use a measurement of about 4" extra for the width. Add an extra one inch length. Cut off 1/3 of width, serge or zigzag all the edges, then using a long bastingstitch, sew the two cut pieces back together with a 3/4" seam. Backstitch on each end about 3/4" and press seam open. On the backside, place your zipper upside down on top of the seam. Pin into place. Stitch zipper on both sides of the seam. Open Seam up to the backstitch. Hopefully you have placed the top of the zipper a little further down so you can unzip it. If your zipper is too long bar tack the end and cut to length. You don't want it in the seam allowance when putting the top on. Serge or zigzag edges of front piece, Put wrong sides togther centering front and stitch about 1/2" seam. around using a regular stitch length. For the corners, stitch on the diagonal about three or four stitches. Then continue on. Trim corner on diagonal. Put ina nice insert and enjoy :)