You can see the hoop he cut for me and the finished mandala before I attached it in the picture below. It measures about 18" across.
I added two rounds of treble crochet to the outside edge of the mandala, one in the front loop and one in the back loop of the stitches. I then placed the hoop between these two and closed the rounds with a round of double crochet.
Ta dah! Here it is in it's full glory!
Don't you just love the colours? I can't get enough of them.