When working crochet in rounds, 3 chain stitches are often used as a substitute for the first double crochet stitch in a round; that is the case here. In the first round, the double crochet stitches are worked inside the ring. In subsequent rounds, the double crochet stitches are worked inside the spaces previously formed by chain stitches.
This tutorial continues on the next page. Page 3: Learn how to crochet round 1 of the granny square.