Part your hair to the side
Use two fingers to..
Separate your hair down the middle
Grab the pony with those fingers and pull through all the way.
Repeat, slightly lower than where you started. Make sure to wiggle your fingers in there as it should not be in the same hole you used before.
Repeat. (Notice that I can only fit my index finger and then i wiggle in the thumb, because it is tight).
Done :) don't forget to tie! If needed I can upload a video, in case I wasn't clear enough.