Con

Just get with the basics your VERY young at your age i was 10 stone and spent all my day in skate parks gaining weight was the opposite of what i wanted to do!
3 days per week train splitting your body into 3 parts (pushing muscles, pulling muscles and legs)
Increase your meals slowly start at 3 complete meals then add meals and shakes until your up to 6-8 meal/shakes per day this will take several months.
For every meal aim for 30 grams of complete protein (5 whole eggs or 150 grams of meat) then once your up to your 6-8 meals add 5 grams of protein per meal until your around 40 grams for 8 meals per day at this stage your body weight will be much greater.
No protein shakes yet no creatine non of that crap, spend the next year training like i said and upping your meals.
When i stated shakes i mean milk with oats not some whey shake its a waste of your money.