Men; what's sex like the first time?

You mean you hope you'll be having sex with your girlfriend. I'm sorry to say, your first time won't last long - like seriously - you're going to really have to think about sports if you want it to last any length of time. The good news is: your 16. You'll be ready to go again in 10 minutes and the next time should last a bit longer. (Sorry, I'm a woman but I thought I'd answer.)