| hey man im with you on this one. I'm 18 years old and I just shot up to 6 foot. I weigh about the same as you. I'm assuming you just had a growth spurt so in the long run, you will pack on muscle and "fill-out". However, this will take a few years so you'll probably stay skinny for a while in a developmental sense. If you want to gain weight quicker then it requires a lot of hard work.
The two ingredients are strength training and a ****-ton of eating. Work out a different muscle group every day and then consume protein and carbs to build up the muscle. Here's my workout.....
monday-chest
tuesday-shoulders
wed-arms
thurs-back
fri-chest
after hammering a muscle group for 30 min-45 min eat protein and carbs until you explode. Don't expect to see dramatic weight-gain in a few weeks because you won't. It takes months to years of constant dedication but it will eventually pay of. Hope this helps. | 
