I am a 13 year old over weight girl. I weigh 180 and I need to lose weight. How can that happen?

Long-term changes. I am happy you are recognizing this problem and taking action. Short-term diets don't have lasting benefits- the key is dietary changes that you can continue indefinitely. One key is to minimize simple carbs. See http://tinyurl.com/hlcchth -this has links to many articles with good information Also see http://tinyurl.com/zhfcohm and http://tinyurl.com/m8avwzh -click on the "discuss that" link.