It took my gf a few months before she could orgasm with me. Of course, I was getting better at it
, but more importantly it just took her time to get comfortable (we were pretty much each other's firsts).
Also, it's all about the clitoral stimulation for her (and for most women from what I hear), so simple intercourse will not suffice, you'll have to rub her while having sex or go down on her (not while having sex though, that might be too difficult
)