WHAT YOU'LL NEED:
Step 1. With right sides facing, fold fabric in half aligning long edges, pin together.
Step 2. Sew long edges together with a 1cm seam allowance leaving short ends open.
Step 3. Turn fabric right way out, fold under 1cm along one of the short open ends.
Step 4. Thread elastic through fabric strip with help of the safety pin. Overlap ends of elastic by 3cm and sew together securely.
Step 5. Insert the raw open end of fabric strip into the folded end of fabric by at least 1cm and pin closed. Sew end together to secure.