Also make sure that you use firm material (tightly woven) and not loosely woven too soft fabric that can pull out from the stitching. Your photo looks like you perhaps did not use a 1/4" seam. If you use such fabric again, make your seam deeper. Ditto sewing them down where they have raveled and then use a decorative stitch to make sure they do not come undone again. Could you glue the fabrics down while you attempt to sew them down once more? Good luck and show us what you do so we can learn from you.