Gather your hair into a pony tail, use a brush if you need. You can then secure your pony with one hairline of you'd like. I did not use a hair tie for this section though but I'd suggest it for ease.
Twist your ponytail from the end so it looks like this
Twist into a circle/bun shape
Here's your bun!
Secure with a hair tie so it'll stay in place
I typically add a headband, but you can accessorize any way you'd like. Use bobby pins and hairspray to secure your stray hairs.
There you have it! What a quick and easy bun :)