Around 1500 calories a dayI need more details to tell you more accurately. If your life style is quite sedentary and you simply walk to school then you should eat around 1500 calories a day and not over 50g of fat (if you're trying to lose weight or maintain your actual weight you should always look at how many grams of fat are in the food you eat. You should never eat anything that is above 12g of fat)
If you're active or very active you should eat between 2000 and 2300 calories a day.