Congrats for starting on your weight loss! I would like to make a suggestion that you start logging all the food you are eating on
www.fitday.com this is a great way to keep track of your calories. I was also overweight in high school and know how hard it can be. If you have any questions at all, please feel free to PM me or just respond here and I'll help you out with whatever I can. It can take a while to lose weight the healthy way, but when you do it this way this helps you keep it off for longer. Good luck and I'm here if you need me.