What would be the best fitness plan for me?

i'm 17 and i wanna get fit, i used to be good in track and field athletics and i was one of the best in my school at one stage, but i haven't done serious sport in along time. I'm in a compound in Saudi Arabia and there's a gym here with basic gym equipment. I don't go to a school, i'm doing it online so i'm basically on my all day. I'm not overweight, but i wanna get fit and toned. I'm not sure on how to work all the equipment and i'm not sure how long i must take on each, I also don't want to risk injury. anyone got advise? thanks