How to half double crochet: http://www.youtube.com/watch?v=XyQoAr74bnQ&feature=relmfu
hdc=half double crochet
Learn how to Crochet - Half Double Crochet
(1) Yarn over and insert the hook into the work (third chain from hook on the starting chain).
(2) * Yarn over and draw through the work only.
(3) Yarn over again and pull yarn through all three loops on the hook.
(4) One hdc made. (5) Yarn over, insert hook into next stitch; repeat from *.