How do I start a conversation with him on Facebook?

[Racecarchick11]

There's this cute guy that I'm friends with on Facebook. We've been facebook friends for almost two weeks. He and I met at a mutual friend's house. It was just the three of us there that time, but I'm shy so I didn't really say much. I made a facebook status about being sick of being lied to and he commented on it trying to be funny and it made me smile. Do I just say hey when I message him and see what he says? or what do I do? Please help! He's 23 and I'm 19 if that matters. thanks!
Oh, he and I have the same car too lol same color and everything, idk if I should mention something like that in my message or what?
Another thing is, I don't talk to the mutual friend as much as I did when I met this guy... So idk how to handle that either.