The french braid looks very complicated, but it really isn't hard. Once you know how it is done, you can begin practicing on creating the perfect french braid. The secret is in getting all the layers pulled tight and keep them there.
This video shows you how to do 2 french braids. If you want just one braid, you would start with the 3 small sections of hair in the crown area and the pull hair from both sides as you braid down.
The real secret to creating a french braid is to practice it many times. The first time you try to create one probably won't be very successful. As you practice more and pull the hair tighter, you will develop your french braiding skills.
Sometimes it may be easier to french braid the hair when it is damp, as flyaways are eliminated from the equation.