Hi Alex... I have some questions I'd like to ask you... Can you tell us how old you are, to start with? What kind of health issues do you have? Have you seen a doctor about them?
The easiest way to stop eating so much sugar and salt is to stop eating junk food like candy, cookies, cakes, sodas, chips and other snack foods. Talk to your parents and ask them to stock up on fresh veggies like carrots, celery, broccoli, cauliflower, and some fruits that you can eat raw to snack on instead of eating processed snack foods.
Drink water instead of soda or fruit juice.
As far as controlling yourself, you're really the only one that can do that. When you feel the urge to eat and you don't really feel hungry, try going for a walk or do some other type of exercise, etc... just do something to distract yourself for a while until the craving for food passes.
Also, make sure you talk to your family about your goals and enlist their help to make sure there's adequate proper food available and that you can get the support you need. Make sure all your medical issues are being treated adequately, because some medical problems can make weight loss very difficult to impossible.