Jane gave me this site to learn the split chain. It is the best. I've watched it several times and my first tries were a little messy. But you soon learn that you want to keep the ds over to the left. And you leave the first half a little loose. Then you pull the second half to tighten the first then pull the shuttle to tighten the second half.
The next row is going to be a heart. I'll show it again when I'm finished.
Here's the site for Maire's instruction on the easiest way to do split chains.