For starters what type of food is available to you? What is your budget? You need to be more specific. Then I can suggest how to construct your meals on a daily basis
Are you in sports? Calories for college students vary because of differences in physical activity. Make sure your diet is mostly whole foods including low-fat dairy, whole-grains, lean protein, fruits, vegetables, seeds, nuts and healthy oils. Don't skip breakfast. Don't get in the habit of staying up late, then rush to get to class. You need food to get your metabolism up, your energy levels will be low and you'll be starving and likely to overeat by lunch. Go into the cafeteria and get a fruit, a granola bar, a hard boiled egg and a skim milk. Most cafeterias offer an assortment of healthy and unhealthy foods. Get to know the cafeteria and when you enter go to the salad bar, so you won't go by the dessert table.
limit yourself to one dinner plate at meals. Use the USDA MyPlate graphic as a guide. Fill half your plate with fruits and vegetables, a quarter with whole grains and a quarter with lean protein. Have a serving of low-fat dairy on the side. This is the link for Use the USDA MyPlate graphic as a guide
You can't eat salads every night. Check the cafeteria's meal plan every week and look for healthy, new foods to try. If need be most colleges have staff dietitian or nutritionist. A nutritionist may be able to help you set up a meal plan.
Other than the above, do what I did, if you can afford it now -- things were cheap when I was in college eons ago -- I moved out of the dorm so I could prepare my own food.