Just an FYI. Even tho you may be a hard gainer, keep in mind your cholesterol and health of heart, etc. Still eat healthy foods. With your metabolism, which probably burns even at night, you can afford to eat more calories. Just keep in mind that you don't want to hit the fast foods, junk foods, etc. and ruin your health.
P.S. Enjoy this part of your life! As you get older, and I'm sure you've heard this, you will gain weight! So have fun! Add weight training and you'll look fantastic! If you can afford to, join a gym and use a professional trainer until you know what to do--if you haven't already! Have Fun!