Start with your hair down, it should be completely dry. As you can see, your hair doesn't need to be extremely long in order to do this hairstyle. My hair is only a few inches past my shoulders.
Put your hair in a high ponytail. It can be neat or messy, your choice. You may also choose to add volume to your hair which I usually do, but I forgot today.
Tease your ponytail. If you don't tease it enough it will look flat.
Make the base of your bun.
Pin your bun down. You can also pin any loose ends in.
How the back of your bun should look.
Hairspray your bun.