First thing I would do is start eating more frequently, no less than 3 balanced meals a day, and keep your portions to one per meal. 2500 calories a day of quality food, lots of water , no sodas or sugary drinks. Do not be ashamed, be empowered everyday and embrace that you want change and are taking steps to change everyday.
Join a gym, do cardio everyday (fat burn zone) for 30 days for 1 hour session. Then you'll be ready to start circuit training.
i am assuming your heart healthy and are not in any danger from medical conditions, you may confer with your doc first if you ae not positive.
join FitDay - Free Weight Loss and Diet Journal to help you log your calories, its easy and effective in calorie counting.
good luck man