Brush any colored hair so there is no tats
Brush only the ends of the rest of your hair.
Pull all of your hair into a doughnut ring.
Spread your hair around it and secure with a band.
Tie a Ribbon around your hair for decoration. (If you want, before this step you could wrap the remains of your hair around the bun and secure with a band.)
All that's left to do is pull the hair from the bun to make it loose.