Women are all different. Some squirt like geysers, some need a damn miracle to get off. Learn the oral and "come hither" thing, works on most.
Well, read up on it - there are some good sites on the internet. It may be that she is too uptight to relax and allow herself to enjoy.
Do you not know how to do it, or does she not know how to enjoy?
In what respect?
She tells you she doesn't like it?