Acording to your profile, you want to lose 13 pounds in a month, so the first thing you'll want to do is relax and slow down a bit. A healthy rate of weight loss is 1-2 pounds per week, not the more than 3 pounds per week it would take to loose 13 in a month. Plus, you are a young person, so I would strongly urge you to really take this slow and make sure you make healthy choices as you try to loose weight.
Loosing excess fat really comes down to burning more calories then you take in (a calorie deficit) for as long as it takes for your body to burn up that excess fat . But, because our bodies are designed to hang on to that stored fat, this can be tough sometimes. You can create a deficit by eating fewer calories, burning more calories through physical activity, or a combination of both. Any of these three strategies can work, but a combination of less calories and more exercise seems to work best for most people, and is best for your overall health unless you have certain medical conditions that can make exercise dangerous.
It would be easier to make suggestions if we know what you've tried that hasn't worked. Again, because you are quite young, I would strongly suggest that you consult your doctor at your next check up, or have your parents make an appointment for you just to discuss your weight. Sometimes young bodies need to hang onto that layer of fat while they finish growing, or there may be another reason while you are having trouble loosing weight. Also, at least according to a BMI calculator (body mass index), you are already in the normal weight range for your height.
I hope that's helpful!
