its all about portions, knowing what you are eating(caloric intake, fat) and exercise. i recommend walking or running 5 days a week. start off easy but push yourself to do more every workout. pushups, sittups, sidebends, squats. plenty of exercises for you to do.

write down a plan for each week and stick to it or surpass it everyday. when you start to see improvement you will be that much more motivated to keep it up and see yourself through.