Welcome to the A-R.

When I was your age I was 155lbs. @ 6'3" tall. It took a long time for me to gain weight. I thought I was eating enough food. Not even close. Back then my favorite supplement was Metabalol by champion. I used to drink that before and after each workout.
Proper diet, clean eating, sensible training, and rest can definitely help you achieve your goals. There are no shortcuts, at your age you should be able to do anything you put your heart and soul into. You've got age on your side and access to the best resource right in front of you.
Keep reading and learning,
otto