It's not your responsibility. However I would advise two things. She goes on top and rides you deep so that she can rub her clitoris on the base of your cock and pubic bone. I think a lot of sex is about association, so even though this isn't strictly a vaginal orgasm, it is an orgasm while your fucking.

Secondly get a prode vibrator and go exploring, find her GSpot and any other spots that do it for her. You could try to stimulate her trigger points while you make love, but I tend to let women who know what does it for them get on with it or tell what to do. Their responsibility.