How do you know how many calories is in the food at dining halls on university campuses??

I have no idea what goes into the food I eat. I try to stick to salads and cereal and chinese stir fries with chinese fried rice. But once in a while, there are other foods that I eat like pasta with marinara sauce; crinkle cut fries, deep fried breaded chicken..and other deep-fried and roasted n grilled stuff...i honestly dont know how much oil goes into these things. how do i keep myself healthy?! im 18 and on the verge of being overweight. i eat fruits and yoghurt at home often... please help!