YOu use wonder under only if you are going to stitch around the piece by machine. In other words, satin stitch around the design. If you are talking hand applique you cut out the design using freezer paper and iron it on the fabric (dry iron) then cut the fabric out leaving about 1/8 the edge around it to turn under while hand sewing. Before putting the last few stitches in pull the freezer paper out, (I use tweezers at this point) You could probably go to you local library and borrow a book that shows you how. If using wonder under follow the directions that come with it. Marge