Being on top help?

Okay, so my boyfriend and I have started to have sex kinda recently. And I feel bad because he's always on top, and I feel like I'm just making him do all the work constantly. There's been times where he's wanted me to be on top, and I try it, but I don't know how. I just don't know what to do, what pace to go, how to move my hips, anything. And it ends up kinda killing the mood, but he tries to reassure it's okay, but I know he wants it. Can someone tell me what to do? How to do it? I know every man is different, but I'm willing to try something to please him