What are you supposed to do while he goes down on you?

The guy I’m with currently and I have never done oral on each other. He’s offered, but I always felt self conscious so I said no. What are you supposed to do while he’s going down? Also I want to try it on him too, but I don’t know how to start that. I’m just an awkward person I think, and I’ve never tried it so I’m nervous about it