Well I am so happy for you! But it is true that some women simply cannot. It is just how they are put together. I for one, am one of those unlucky women. Well, not really, I can cum just not from penetration. But, yeah, let us know how you did it!
And for those who need some help in this area, I have heard(although it does not work for me) to stimulate your clit while having intercourse. But damnit, make him do it for you!