Interfacing is fabric on one side and glue bumps on the other. Trace the paper pattern onto the fabric side of the interfacing. Cut the interfacing a 1/2" outside of the drawn line. Repeat for the second side (two are needed, one for each side of the bag). Lay the interfacing glue-side down on the back of each piece of tie fabric. Iron the interfacing so it starts to fuse to the back of the ties. Start from the middle and work outward so that you won't have any bubbling. Pin the tie fabrics together, pretty to pretty, and sew around the two sides and the bottom of the bag. When that's done, turn it inside out.