Time Turners- Hermione's Secret for More School

So, in the Prisoner of Azkaban, Hermione has a time turner. A time turner is a magical object that allows the person wearing it to travel in time. It is very dangerous though, as most "witches or wizards end up killing themselves," but Hermione doesn't really care and convinces Professor McGonagall to let her have one so she can attend more classes? If I had a time turner, I would do something way cooler with it, but eventually Harry and Hermione go back in time to save Buckbeak and Sirius, but it is mostly used for shcool work by Hermione.

So, I think that the way you use one is by turning the time turner backwards or forwards, and you go to the time the amount of turns earlier or later. It has a small hour glass on it and a few rings that turn and spin. Time Turners were destroyed in The Order of the Phoenix during a trip to the Ministry of Magic.

http://harrypotter.wikia.com/wiki/Time-Turner