The first step, though difficult, is the healing step. Have faith in yourself and the fact that there is a treatment for it.
If all your life, you have been having problem shedding weight, then probably you have disorder like a thyroid problem, diabetes, or an adrenal gland problem. Treating these problems can help you lose weight considerably.
A positive frame of mind is very important for treatment. If you have the will, you'll find the way. Join support groups to keep yourself motivated. Take up yoga for that will help you. Join any good center in your area. Apart from this, you need proper diagnosis and treatment without which success is not possible. The treatment involves various types of behavior therapies, nutritional guidance, medications to control hunger, food satiety, and exercise and yoga. Please consult a good psychologist/psychiatrist who specializes in eating disorders. Take care!