help finding a pattern/directions

I found directions in my aunt's things for a potholder. It starts as a rectangle and by folding and stitching it becomes a square. HELP. Here's what I have: Chain 40.Single Crochet down one side of chain and up around the other side. Keep going for 18 rows. Stop between start of chain and first row, leave quite a long tail of yarn, and fold the two ends together in the middle and close neatly. ??????????? Any help will be greatly appreciated. I just feel that some of the directions are missing.