Use the 'results' to measure out two identical pieces. Sew the straight edges together, and you've got a skirt! You'll probably want to use a zipper, buttons or string to hold one side together so you can get in and out of it... or, if you make three pieces, you have a lovely wrap skirt. But anyway, here's how the measurements go together.
The 'degrees' you put in will determine how much flare the skirt's got. It also determines where you put the tape measure. If you put in less than 180 degrees, pin the tape measure outside the fabric like this and swing it around the inner and outer radii:
On the other hand, if you put in more than 180 degrees, the tape measure will go inside the fabric and swing around the top:
(click on either image to see full size)
The idea is that you can play with the degrees setting to get pattern that fits the fabric you have. Lovely!