It's not an unocmmon phenomena for it to be painful for a woman the first time, or indeed the first few times she has sex.Make sure that your partner takes things slowy and steadily, plenty of foreplay before you even attempt penetrative sex. It's a new sensation for you ,sharing your body with a man, and you have to be ultra-relaxed and ready or you will tense up and it will be painful for you.If your partner is also inexperienced then he may be a bit over eager and rushing things, so just make sure he isn't too "bull at a gate" about it and all will eventually be well.