Here is a triple single Rainbow Loom bracelet that I made for my son. It’s easier than you might think, although getting the beads on was the hardest part. I used letter beads from Michaels and put them through the center chain. As I was doing a loop, I would pull the rubber band up and hold it with my fingers to thread the bead through before looping the band on the next peg.
Here are a couple of links to videos that show how to make the triple single.
This link is a downloadable pdf file that shows the instructions step-by-step.
Here is a link to a clip of New Jersey governor Chris Christie talking about his daughter making Rainbow Loom bands: