Having a hard time keeping a conversation

A little context: I've never really talked to a guy before much less flirted. I mentioned to my friend how I thought this guy was cute, my friend took the initiative to dm'd him saying that without me knowing. Said he thought I was cute too and we ended up getting eachother's phone number and texted for a while. Only issue was I had a really hard time coming up with a conversation, much less things to say and it kinda just died completely..How do I strike a conversation? Much less keep it actually going and lively..I'm sort of awkward and really closed off when I don't know someone. I just shut off and am usually at a loss for words.. I'm kind of embarrassedTl;dr I don't know how to talk to boys and I wanna get better even if it's hardly anything serious.