It isn't hard, just measure the width where you want it, measure the length you want flap, about 5 inches, cut 2 pieces of fabric, one of thin lining, sew right sides together with lining on one side, turn right sides out, sew into purse at seam line between purse and lining of purse, then sew you purse and lining together on that top edge. You may use velcro or buttons or snaps. Hope you understand what i'm saying.