I would throw out the weightgain 200 from GNC, it's basically just maltodextrin and whey. Obviously you would need to increase your calories, and get 1.5x your bodyweight in protein.

Now, as far as training goes, you wont get far with what you have. You need to be able to squat, and ramp up weight in everything you do. Since the goal is to get stronger every workout. If you're really serious, go to a gym and just do it. Because it'll be a whole lot more expensive to buy all the stuff you really need if you're serious.

You ought to squat 3 times a week and increase 5lb every time for as long as you can (you can get a shitload stronger on the squat so you would want to do it as often as you can increase). Bench press, overhead press, barbell row, chinups, are all great for the uppre body. Do those once or twice a week and increase as often as you can. And deadlifts are great also but I would do them a little less frequently since they are a very taxing lift. You can increase 10lb a week on these probably.

Well that's the advice I have as far as training goes. Do those lifts and get brutally strong on them and you'll grow like a weed. Once you start in the Army you really dont have much choice but what they tell you. Their training isnt exactly optimal for mass building so dont bother once you start with them. Just eat as much as you can and hope you can at least maintain your weight once they start training.