Work 3 sl sts (2 sl sts with the old color, and join the new color in the third) so that your crochet hook is adjacent to the space formed by the closest set of chain sts. Ch 3, 2 dc in space, ch 2 to form corner, 3 dc in same space, ch 2, (3 dc in next space, ch 2 to form corner, 3 dc in same space, ch 2) 3 times, sl st to join to the 3rd chain stitch you crocheted at the beginning of the round.
There is more info on page 5: See how to do round 3 of the crocheted granny square.
