Log in with Facebook account on site function

Hi.. Im looking to hire someone that can create me a function on my site where people can log in with their Facebook accounts to my website, you need to know what your doing since i will want you to edit my current site so when they log in with Facebook accounts to my site it will keep their stats (not password or so) my site is a music search engine, when people log in with Facebook accounts they may create playlists that will need to be there for next time they come back.. Let me know if you can do this and how long it will take.. the URL to my site will be given via PM by request.