Harry Potter 7 Question? Don't answer unless you want it spoiled.?

In the 7th book towards the end, when Harry is walking to the Forbidden Forest to give himself up to Voldemort, he opens up the golden snitch and inside is the resurrection stone. What I want to know is how did Dumbledore get the resurrection stone and whether its voldemorts grandfathers or mothers. I read the book a while ago and forgot. Please and Thanks.