You just pull your hair into a messy bun (or super sleek bun if that's your thing) on the back or side (or top or front- I guess) of your head and screw them right into the bun, one from the top and one from the bottom. They hold like magic and require no pony tail holders!! Couldn't be easier! Best thing is you only need two! (unless you wanted to make little buns all over your head then you would need two per bun but that would be weird- don't do that)
I found mine at Target after seeing them in a magazine but think they sell them at drug stores too.
Cheers to hair success!