How to get my Iphone 4s to work?

So my friend lost an iphone then got a new one THEN found the old one… So now i have it. How do i get it to work without getting tracked or going to jail or something like that?

You can reset the phone. It's in Settings somewhere. After you reset it, then you can hook your Apple iTunes account to it. I got my first iPod (used of course) from Craigslist, so I would know.