Well, you can always let him know that it's actually illegal and he can be charged if he has sex with you, but I would hope that he respects you enough to accept when you say that you're not ready. It's quite simple - if he can't wait for you, he's not worth the trouble.
u shud support him by agreeing to him.u r not too young.i know it wud b a bit frightening bt its ok.u shud have sex cz at this age ur soft n sexy intimate organs will feel more pleasure
well if your not ready then tell him and if he doesnt understand then you may have to end it or end up doing it and regerting it later.
Reading my mind are you? :P