Cut off the zipper of your dress so you have a big space in the back. Don't discard the extra fabric, you will be using it later.
Sew the edges.
Using the extra fabric, cut small strips and sew loops along the sides. At the top, cut long strips of the black satin fabric and sew it on.
Lace up the dress like you would with shoelaces and tie a pretty bow.
Of course, only do the above step when you actually put on the dress. I just laced it up to show you :)