When you feel inexperienced, concern about your partner's prior experience is natural. Actually, this feeling tends to begin during our early sexual experiences. Remember when you were an adolescent and you experienced your first make-out session (or even first kiss)? You were anxious, you were scared, but everything turned out OK and you learned from that experience, right?
You still learn from such experiences, in your 20s and beyond. I think you should be excited about the fact that he is very experienced because you'll have the opportunity to learn from him. If you're really lucky, the experience he has acquired over the years will translate to his knowing what he's doing when it comes to pleasuring the female body. If you communicate openly with him, you can teach him to use those fabulous skills to do exactly what turns you on.
If you're comfortable enough with him, I would strongly suggest telling him you're a virgin and express your concern. This will allow for you to bask in the learning environment without feeling self-conscious. He will likely find it a huge turn on to know that he has the opportunity to teach you so much between the sheets - like working with a blank canvas!
It is entirely possible for two people with really different levels of experience to have good sex. Actually, those two people can have great sex! Sexual compatibility has very little to do with previous experience and a lot more to do with the dynamics between those involved. You might find a combination of folks who both have a lot of experience but just aren't compatible with one another, or a combination of folks who both have no experience but just aren't compatible with one another. Then there are others who just really work well together, regardless of experience; that's compatibility.
Also, you can build compatibility with one another by communicating about your sexual likes and dislikes (once you get to know them) and understanding each others' sexual personalities. Are you both creatures of comfort? Or is one of you a thrill seeker? Get to know one another in this way, through lots of fun practice, and open communication. Even if you aren't naturally compatible in terms of sexual likes and dislikes, by communicating comfortably about sex, the two of you will be far more likely to be able to meet in the middle and become compatible.
I hope that you'll become excited, rather than concerned, about the prospect of exploring your sexual compatibility with this partner. Once you gain a little experience with him, make sure you're comfortable enough to communicate what you like and don't like sexually, and enjoy the fact that he has some pleasure tips and tricks to share with you.
Kristen Mark, M.Sc., is currently completing her PhD in health behavior with concentrations in human sexuality and statistics at Indiana University. She is a researcher at the Center for Sexual Health Promotion and researcher and writer for the Kinsey Institute for Research in Sex, Gender and Reproduction. Her research largely focuses on sexuality in the context of relationships; maintaining sexual desire; and sexual quality, pleasure and satisfaction. For more of Kristen, please visit Good in Bed.