Re: Why can't I pleasure my girlfriend?
This might help you to understand.
If a baby becomes a male, a penis develops. If a baby becomes a female, a clitoris develops. Concentrating on the vagina and ignoring the "button" would be like a woman concentrating only on your testicles and ignoring your penis. It's not that you would mind, but it probably wouldn't get you there.
As the other response said, go easy and gentle. It can be a sensitive area. And as you get more advanced, maybe you'll find that "g-spot". But some women question whether that even really exists. But almost all of us are certain we have clitoris'.