From the measurements you wrote, your weight is between the 25-50 percentile and your height is just above the 10th percentile for your age. You are under 20 years old and need to track your weight and height on a children's Growth Chart. You are normal for your age (not underweight or overweight). For healthy eating, eat a Heart Healthy diet which means a moderate fat diet to lower the fat content of your foods, increase ‘good’ fats to benefit your body. Moderate fat diet means = use polyunsaturated (omega 3, corn oil, nuts, etc) fats and monounsaturated (olive oil, canola oil, peanut oil, etc) fats, no saturated fats (high fat snack foods, butter, fat spreads) and no trans fats. Eat low fat meats (chicken, fish, loin of pork) or non-meat sources (soy products, nuts), low fat vegetarian combinations (rice & beans, pasta & beans, low fat cheese & pasta), low fat and substitute dairy products (1% milk, low fat/fat free yogurts, low fat soy milk/soy yogurt), use plant oils, non trans-fat margarines, and eat a lot of fruits and vegetables. Eat daily high fiber breads and cereals (oatmeal).
As for exercise, you need to do activities that are fun and do physical movement. Dancing and jazzercise are fun and you are burning calories doing them. Swimming games and swimming dancing or exercising are again fun and burning calories. Join a bowling league or any type of sport. Maybe do yoga where you learn to stretch your muscles and tone up your body at the same time. Walking is also the best form of exercise and you can simply do that by increase you’re walking to 1/2 hour a day. That 1/2-hour can be broken up through the day, 10 minutes here and 20 minutes there. Hope this helped to give you some ideas.