How should a guy touch a girl when they have sex???????????

I was alway curious to how a guy (mid 20's early 30's) touches his girlfriend in an intimate way for sex? My boyfriend puts his hands on my lower back and moves them up and down and then goes to my upper arms and than does the same thing. Just curious. But how should he approach in telling her that he is sticking his penis in her vagina? I am serious and not a troll either. Just curious.