I know it's probably a little late to give any advice but really I think all you need to do is relax, be comfortable with one another. If she's more experienced than you then she'll likely take the lead and do everything she can to make you feel comfortable and take things at a pace that works for you both. If you're both of the same level of experience then you can explore together without any pressure, communicate, discover and explore, most of all - enjoy yourself. That's the most important part - it's the most amazing, thrilling experience to share with a woman you love, cherish that, as you learn one another's bodies and what you each enjoy then the experience will become better and better. At least that's been my experience.
Remember the point is to make one another feel good, to express that connection you share in a loving and mutually satisfying way. There's nothing wrong with being nervous - that's a natural and good thing, it means you care.
I'm sure this is all a bit late in the day for advice and you know all of this for yourself now but I haven't been online for a while so thought I would reply.