the cheapest form of cardio is to walk/jog/run around your neighborhood I mean it is free, second if you want get a bike, an eliptical might be expensive. swimming if your school has a pool. you can also lift light weight but do more reps in a period of say a minute to get your heart rate up instead of lifting for max weight. to make it easier you might just want to join a gym. there are some gyms here in the states that are cheap as 20 bucks a month.

as for eating healthy eat 5-6 times a day, HEALTHY FOOD!! not chips shakes, fast food, etc. watch portion size, eat lean meat, more chicken (no skin) and fish then steak. write down what you eat throughout the day to keep track so you can see how you did throughout the day.