I need help losing 43 pounds?

Ok well I'm 16 years old and I weigh 213lbs and I'm 5"6. I really need to lose weight, I've been fat my whole life and I'm sick of it. I was wondering if anyone could help me make an exercise and diet plan. I already exercise.I walk on the treadmill everyday for 1hr, I dont think this is enough, I think I need to exercise more because I stay at home all day and usually just sit and watch tv, and for food well for breakfast I have Special K cereal and for lunch I usually have a sandwich, and for dinner I usually eat whatever is made. I drink like 4 gles of water everyday as well. I have a problem with snacking between lunch and dinner, I just go into the pantry and eat whatever I see. I cant tell my parents not to bring that kind of food because I have a little brother and the snacks are for him. Also I don't want to try any diet pills or whatever I just want to exercise and eat healthy. Also I cant go to the gym. I have a treadmill and a stationary bike that's basically all I can do. I know I can't lose 43 pounds before school starts but I'd like to be at least in the 100's by then which is in like 7 weeks. So if anyone has any ideas I would really appreciate it.