The next step is to stitch the fabric down to the ribs. Apparently the idea is to keep the fabric from vibrating or bouncing around too much in flight. There is a particular method to exactly how the ribs are to be stitched. With a long needle, I push it through top surface and come out the bottom. Then around the rib and back up through to the top side again. And then I have to tie this complicated knot. I had to watch that section of the video about TEN times to learn how to do it. No kidding!