If you don't know how to inside-outside french braid, do a normal french braid. & if you're not sure on how to do a normal french braid, you could easily just do normal braids starting at the top & bringing them together to the pigtails.
Part the hair down the middle. Secure one side with an elastic to stay out of the way. Part the first section that you are going to braid & secure the rest with an elastic.