I love this hairstyle, too! and it's great because I did the previous style one day (with loose curls in the back), then the next day I added the braids and twists up the back and left the hairdo in her hair for a few more days after that! (Which is nice if you don't want to - or don't have time to - do hair every day. It's also nice because braids can be very beneficial to hair.)
Basically, just keep braiding! I alternated braids and flat twists. and I aimed them all up toward my previous ponytail.
If your child is old enough, you can have them lay in your lap for upside down braids like these - otherwise I just let Q keep watching her movie and I stand backwards and "braid up"! If that made any sense at all!
Then I put all the ends in a ponytail.
and looped another hair tie around to make a messy bun.
Right side view....
Left side view....
Then add the accessory of your choice!
And lastly, a picture of a very proud Q showing off her clay creation! :D