First time to gym tomorrow, any tips? ?

So in one year when I go to college I am doing Air Force ROTC and there are strict physical fitness tests. So I want to go to the gym and work out. I am 5'10" 165 pounds. Male obviously and I'm 18 years old haha. But I've never really been to a gym and do you suggest any machines? I want to be able to do 50 push ups in one minute and 40 sit ups in one minute. Also run 1.5 miles in under ten minutes. Currently I can do 20 push ups and 25 sit ups. I can run the mile fine though. And what machines to get a six pack?. But what machines do I use? And all the details and tips so I don't look like a fool. Ps I'm going around 9am when all the housewives and people are gone at work. Thanks in advance!!