long distance relationship

Hi, I'm 17 and I've recently started seeing this guy. He lives a few hours away from me and things have kinda started to get serious with us. His parents know about me but my parents don't know about him. I've never been in a relationship before so I'm not really sure how to tell them. I'm not sure how to tell them how we met either as we met online! We've met up a couple of times and he's a nice guy. Please help!xx