1. Insert bag body inside bag lining with right sides together; the handles and button loop should be between bag and lining. Align raw edges and seams. Stitch together top edges of bag body and lining, backstitching over each handle for reinforcement.
2. Turn bag and lining right side out through opening in lining; hand-stitch opening closed.
3. Insert lining back into bag and press top edge. Topstitch 1/4" from upper edge of bag.