This hairstyle is a two strand braid. A two strand braid isn't really like a braid, it's more like weaving your hair. Although it is a little hard at first, but after a few tries you'll be a pro. I personally get really excited whenever i concur a new hairstyle. To start this 'braid' make your hair into two strands, one on top and one on bottom. For this hairstyle you're going to need rubber bands, lots of them. Take the top strand and wrap a rubber band (hair rubber bands of course) around it near the top leaving some space. Separate the hair above the rubber band, making a space to pull the bottom strand through. Now that the bottom stand is on top wrap a rubber band around that strand and make a space. Pull the strand on the bottom through the space, so now its on top. keep repeating this process until you have completed the whole braid. secure the braid at the end with a rubber band or regular hair tie, whatever you prefer.
I did my two strand braid on the side of my head, you can do it on the back but it would be extremely hard. Always try new things, don't give up until you get it, I got it. I practiced on my mom before myself.. try it on someone else first.