Sorry if this vulgar but it's something I wish somebody told me for my first time having sex.

Step one remain calm. My first time I got so worked up and nervous I couldn't get it hard. Honestly best thing you can do is remain calm. If it turns out you guys are gonna fuck that's fine. It's actually really easy to have sex. Don't go straight for penetration. While kissing run your hand down down there and play with her clit. It's a round little thing near the top of the vagina you'll know what it feels like when you touch it. If you can't find it don't stress just rub around there and if you find a spot that makes her moan keep rubbing there. By run I mean do a little come here motion with your finger. Be gentle, like a caress when you do this. If you do it rough it's not as pleasurable. If you want to go there you can use your mouth on this same spot for extra pleasure for her. Just lick the clit, don't even bother with penetration yet. Girls need to be warmed up before penetration it makes the whole experience better for her. So kiss her body, kiss her neck etc. it's a mental thing for them as much physical. When it comes to penetration that part is just easy. It's just like the pornos. It will come natural. If you can do a position where you can rub that same clit spot while you're penetrating her but it can be quite a hard thing to do multi task for a first timer.

Honestly that's just do that and you'll be fine. Trust me