The first thing you have to do stop eating junk food and drinking soda. You could lose several pounds fairly quickly by doing those 2 things.
Eat plenty of vegetables and lean protein. You have to calculate the number of calories you need/day; you can't go by what another person recommends, because what's right for them, might not be right for you. It's based on your individual height, weight, age and activity level. I can help you if you like or you can look for an online calculator.
You don't need a gym to exercise. You can try walking for 30 minutes/day, or go online and check out exercise videos to find some you might enjoy doing.
Hey, I am also 16 & I weight 177 pounds, but I am 5'6 & I am trying to lose 20 lbs, if you want advice or help with anything, let me know. My doctor recommended 3-4 times a week workouts & eating 1500 calories a day, COUNT your calorie intake! :)