What should i do if a boy wants to finger me?

I'm 15 and i'm going to a disco in 2 weeks with all my friends. A boy i like has asked me to "meet" him ("meet" is the irish word for french kiss) so i'm thrilled. My friends have warned me that he likes to go "down there" aswell. I'm inexperienced with this stuff but i'm totally ready to get experienced. I really like this boy but im nervous and worried about fingering cos it's new to me, my friends have done it and say it hurts for the first while but it feels great. What should i do if he puts his hand down there? Should i groan? Do i shave everywhere? What underwear to wear? I'm clueless so pleeeesase help!