If you want a twist around the base like Carrie's, just leave a section of the pony out on step 4
1. Start with a high (or low, depending where you want your bun) ponytail
2. Cut the toe off of a sock that matches your hair color
3. Roll the sock in a doughnut shape
4. Place the "doughnut" at the end of your pony and begin to roll the hair around the sock
5. Keep rolling the sock down until you reach the top of your head... and voila!
If your hair is shorter or extremely soft, you may need to secure with bobby pins.