In a private but non-sexual setting sit down and have an open and honest non-judgmental conversation with the guy. No interrupting each other, explain yourself in full then open it for questions or thoughts. After that, throw the metaphorical ball to their side and let them talk uninterrupted. Go back and forth like this as long as needed to reach a catharsis and come up with a plan to redress the issues.

Frame it with something like "Hey, I know you're inexperienced with this stuff and that is perfectly okay. We all start somewhere and we all have to learn as we go, this is no judgement against you...". Then open up and tell your partner what you've mentioned here. Let them tell you how they feel (and reassure them if needed). After that, ask your partner if they would like to talk about some things they like, dislike, and/or would like to try out themselves. That way you have a give and take equal footing conversation.