I think that you know what to do next, but slowly build up from just kissing, then licking then taking the end into your mouth and sucking. Then try to get as much of the cock into your mouth as you can, letting it go into your throat if you can. Try to relax and hold your breath as you go as deep as you can. When you can’t hold your breath any longer back off and breathe. Then do it again. Keep doing that until your nose is rubbing on the man’s pubic hair, if he’s got any.
When you think that he’s about to cum, back off and ask the man where he wants to shoot his cum. If he says your face or mouth, try to catch as much as you can with your tongue and keep it in your mouth.
When he’s finished, look up to his face and hold your mouth open so that he can see his cum in your mouth. Once he has seen it, swallow it then open your mouth so that he can see that you’ve swallowed it all.