To answer your question about turning the rectangle into a skirt, position your rectangle, so you are looking down the satin middle with the chiffon peices to the right and to the left, right sides up.

Take the bottom and fold it up so the bottom edge is even with the top edge (right sides together). Sew across hte top edge. (As you are sewing, you will sew across one layer of chiffon skirt, then across the waisband, and then across hte other layer of chiffon skirt.)

Turn it right side out and grab the middle of the waistband in a couple of places. Then make one of your chiffon skirts fall to the inside of hte other one.

Is that clear as mud?