I'd suggest you ease into it - two little tihing you might like to try.

1) When you start making love, and you're just about warmed up, Roll him onto his back without asking, ignore any suggestions and cowgirl him. When you do this, put your hands on his chest or shoulders to hold him down, and order him not to cum until you let him (after you've had your fun). Just take you pleasure using him and see how he reacts.

2) Start as above, then get him in a reverse missionary position. (On his back, knees spread and as high up as you can get themhis cock inside you. You'll have to put him in first, and then get between his legs and bring his knees up - you can even put his feet behind your back.) Now fuck him hard - again with no permission to come before you do. If you look down between you, it's hard to tell if that slippery cock belongs to you or him. Keep telling him you're going to fuck him until YOU have had enough.

Both of these woman-on-top-and-in-control positions will give you both the chance to find out how it feels, and you can move on to the other things suggested as you feel comfortable.