Please, I need help in gaining weight?

I'm 17 years old... my weight is 39 KG and my height is 165 CM... Several times i had a drop in the immunity system and I also have anemia [it kind of comes and goes every year]... I never remember that I've actually been of normal weight since I was 5 years old of something; I remember that at the age of 8 I was about 20 KG. I also have this problem that I never actually get hungry, like I could live for a whole day without eating anything but a piece of candy. In addition to the fact that I feel full after eating very small quantities of food [like two full spoons of fried rice, for example]. I also get taller very quickly but NEVER fatter. Like once I really adjusted my eating pattern, in fact I used to eat a lot at that time, but all what happened is that I kept growing taller during that period! I really need someone to tell me what to eat and in what quantities exactly everyday... because I'm having health problems because of the fact that I'm underweight, and ever small physical effort makes me EXTREMELY exhausted.