You need:

Fleece fabric

Elastic I prefer 1in No-Roll (measure waist then Minus 2 for example if the waist is 21 inches you will cut 19 inches elastic)

-          Measure the length and the widest part of the skirt; those are the measurements for your rectangle. 
            (My measurements: 14 inches length, 19 inches wide)

-          Cut 2 rectangles with the measurements

-          Cut several strips of fleece about 2 inches wide,  I had only short pieces left, so I sewed several small strips in 1 row.

-          Sew a long running stitch down the middle of the strip, gather to form ruffles

-          Sew strips to skirt however you like

-          Lay the skirt pieces right sides together, and stitch up the sides of the skirt, making certain the tops are matched up

-          Fold top part down about 2 inches to create a casing for the elastic, stitch along edge leaving an opening for the                    elastic

-          Loop elastic through the casing, sew ends  together and sew the opening shut

-          Done