But how do I get over my fear?

I'm afraid that I will do something wrong or not be good. He has been with other people sexually and i'm so inexperienced. I just feel like i'm not going to know what to do

So, i'm 17 and I have never done anything more than makeout. I'm starting to get into a serious relationship and i'm really freaking out because i have no idea what to do. I have never even seen a penis in real life :| so i keep trying to get over it but i get really bad anxiety even thinking about ...