I got off to a few false starts trying to watch a video (not tatting related). I should have known better when I was trying to learn something new. This is the only one worthy of showing. As you can see, I was making the double stitches in the correct places with nice picots, but they are not alternating. All red ones are to the front; all yellow ones are to the back.
So, I tried again. I had loaded my thread onto two shuttles. The hardest part of this for me was making sure that the threads were in the right position to overlap. I ran out of thread on my shuttles (remember all of those false starts I mentioned earlier), so I reloaded shuttle one and just used the loose thread from shuttle two as a ball thread in tatting the second ring. Oh, that was so much easier. If I forgot to concentrate and keep those threads in the right position, I just grabbed my crochet hook and pulled that loose thread through where it belonged. Muskaan has provided lots of detailed pictures to help us all out. They are linked from the class website or you can go there directly.
This is another design element than can replace a ring in our tatting. The main appeal to me is the effect produced by using two colors. While I have no immediate plans for its use, it's fun to learn something new. I also have another technique I can use when I just want a slightly different look in a familiar pattern. I'll definitely add this into the next update of Element-al Approach to Tatting Design.