That tutorial is slightly different than how I made mine. My squares are 3.5'' square. 18 of each color. I sewed them all together to form a 18'' square peice. I then right sides together sewed it closed to form a tube. Turned right side out and ironed. Then folded over a 1/4 inch amount on the bottom, and installed the elastic. Folded the same over on the top, stitched it down. Insterted my hanging material (like I would a drawstring in sweatpants) and then folded it over double to hold it tight.
I can get more detailed and do some pictures if ya'll want!