The opening to my vagina hurts and it's painful to have sex. what can i do about this?

Several things?: First of all, try one of the many lubricants available for just this purpose. Secondly, try different possitions in intercourse - even a slightly different angle or a pillow under one of your "butt cheeks" if you are on the bottom. Positions with you on top may give you greater control over pressures exerted. Gentle stretching may help; see your doctor if not for a referral to a sex therapist.