They really should either show you how to use them or include instructions. they are pretty easy once you figure it out tho. I am assuming you bought the ones from DL or WDW right? If so this is how you use them.
You should have a small allen wrench with the back, you place the end of the wrench into the black hole on the backing, unscrew it until you can slip it on your pin, you don't need to unscrew it all the way, just partway, then slid the back onto the pin post and tighten the wrench. that's it.