Right. So. This is about the easiest thing to make in the world ever. It literally took an hour. It's made from a rectangle of fabric, and one piece of elastic (well, ok, there are two little heart shaped pieces for the appliqué as well, but let's not split hairs).
I measured madam's waist and cut a length of elastic accordingly. I decided how long I wanted the skirt to be, and added about 10cm to this length (to allow for the elastic casing and the hem). This is the length of the short side of your rectangle, and the long side will be double your waist measurement.
Sew your two short edges together, finishing the seam however you prefer (I used a french seam because my rescue machine doesn't allow me to adjust the stitch length of my zig-zig, and because a serger is little more than a distant daydream). This will leave you with a wide tube.
Hem the lower edge of the tube. Fold over the upper edge to make the casing for the elastic, tucking the raw edge under itself and remembering to leave an inch or so open so you can get the elastic in. Rookie error that, stitching your elastic casing closed before the elastic is in it. Never done it myself of course. Ahem.
I topstitched along the upper edge of the casing too, just 'cos I thought it looked nice, but don't feel like you have to. I'm not the boss of you. Thread your elastic through, stitch the ends together, making sure that it is not twisted, and sew up the gap in the casing.
Voila! You made a skirt. Wasn't that easy?
So easy, in fact, that I felt a little unsatisfied by it and decided to appliqué a heart onto it. There's nothing stopping you from making one in grown-up size either....