Start with a high-low dress (or skirt) or cut a regular skirt so it goes up in the front.
Next measure the distance from the back of the skirt to the front. Make your ruffle 1 inch wider than that. Measure the front of the skirt and make your ruffle 1.5 X longer than that measurement.
Finish the edge of your ruffle (I did a simple rolled hem).
Then finish the top edge and gather.
Pin the ruffle to the underside of your skirt front angling the bottom hem up like pictured above.
I serged off the extra ruffle. If you do this be extra careful not to catch any of the dress in the serger. Alternatively you can just tack the extra ruffle up with a few hand stitches.