If you have not done this before, lock your door, put on a bright light and take a mirror an look at your vulva. It is important for you to feel comfortable with yourself before. Pull and feel every part of your genitals. If you have not done so before, masturbate to find out what feels good for you and how you like to be touched. If you did not do this first, you have no way of helping your bf to please you.
Get a bottle or tube of lubricant and make sure that you have condoms on hand. Relax and enjoy.
If you are not willing to do this or have not done this yet, you are not ready to have sex and you should wait until you are more comfortable with yourself and your own sexuality.