Sex is a natural part of God's plan for human beings. It is one of the most beautiful parts of a marriage.--two people intimately connected. As a woman you can learn to enjoy sex and find a lot of fulfillment. In fact I look forward to making love with my husband whenever the time arises.
Think of sex as a way to tell him how much you love him. There is nothing to be ashamed of. It is all a part of God's wonderful design.
Having said all of that, I can understand that it may seem strange at first. Be patient and gentle with each other. You might also read some articles on sex in marriage. There is plenty of stuff out there that will help you with some of the techniques and ways to perform. It need not be "dirty". I have a feeling that after you are married it will all work out. Relax and enjoy