at 17, I was about 160-170 lbs 6'2". Also a hardgainer.
My advice:
Eat big. It's the hardest part of building your body and in my opinion, the most important. Eat 6 times a day!! It sucks but you have to do it. With my schedule, I have to drink 3 Myoplex MRPs a day in addition to 3 healthy meals. You look a little predisposed to some fat, so cut out ALL soda, chips, french fries, candy, etc.
Training. Start with compound movements, only 3-4 sets per exercise and only 2-3 exercises per bodypart. Squats, bench, military press, deadlift, rows, etc. It's better to start off doing to little than to much. There are a lot of beginner or hardgainer routines on the net. Just find one you like and post it here for review.
REST. Often overlooked. REST REST REST. You grow when you're resting, not at the gym. Sleep is the most important thing and it's when you grow the most.
Training Log. Should be as necessary as eating. Keep a log of your routines and make notes in the margins. Training logs are personal and no one can tell you how to keep one. You have to get your own style.
I'm still 6'2" but I'm up to 198lbs. Took me 3 years to get here from 170, but you can throw 2 knee surgeries and a dislocated ankle into that. I was stuck in a plateau recently and thought I couldn't gain anything more. I reviewed my eating, lifting, and resting patterns and found places to improve. I credit a lot of that to my training log. Since my overhaul, I've gained 3 pounds in 3 weeks and my strength goes up every week now.