How do I stop being Skinny?

I am a fourteen year old guy and I am extremely skinny. My wrist bone sticks out like my wrist is broken, you can see my rib cage like I haven't eaten in years, I'm just too skinny! I really want to gain some weight and look normal. Basically I just want a diet that I can have to gain weight, but still be healthy. I also want to workout to have some muscle.