Turn sling with wrong sides facing and gently press all seams. Press under a 5/8” hem on the top rail of both fabrics, pin lining to fabric. Insert one side of zipper (the side without the pull) centering the zipper at the curved seam. The zipper will be sewn in between the lining and fabric. Top stitch the top rail together securing zipper in place (using zipper foot). Top stitch lower rail and curved seam if desired.