This tutorial will guide you through making this double-sided ruffled and frayed pillowcase for any size of pillow insert. You could make it for your pillow on your bed, or a pillow sham, or a decorative couch pillow.
With right sides together, lay those two pieces together evenly and sew 5/8 of an inch away from the edge of the long edges, or the top and bottom of the pillowcase.