Well, first things first, if you're serious about this, I highly suggest that you either get a gym membership (if your school doesn't have a strength and conditioning gym) or get some home equipment. Whether you train at home or in a gym, the most important equipment for you to get/access is a power rack with Olympic barbells and weights of all sizes. The second-most important equipment is dumbells (adjustable dumbells if training at home; gyms typically have entire racks ranging from 1kg-50kg.
Using that equipment, a simple fullbody routine is all you need. Do the program as written, do everything with good form, and keep at it for as long as possible. If you read fitness magazines, they'll tell you to change programs every 6 weeks. Well, you'll see that in the program I'm linking you to, you don't even add more weight until 6 weeks in. That's okay, because there's no get fit quick scheme that works - whereas on this program you can last for a very long time, with people often adding 100lb onto the big lifts and 10's of lbs onto their frames within 12 months. If for your 17th bithday you'd like to weigh 160-180lb and be able to bench press 200lb and squat 300lb, this program, with appropriate diet, will get you there.
Which brings us onto the food component. As you hopefully already know, eating less makes you smaller, eating more makes you bigger, and your training will define what kind of what gain/loss is to be made either way. So, the most basic thing you need to be doing is eat more than what you're currently eating.
The kind of training you're doing will of course burn calories within each session, but it will also cause your metabolic rate to elevate by about 10% (give or take) for the next day (give or take) after training, and the increase in muscle mass will generally result in higher metabolic rate. So, assuming that right now you maintain body weight at 2000kcal/day (which is just an assumption used to make the math easier), you'll probably burn 200kcal in each session, burn another 200kcal over the next 24 hours, and increase your resting metabolic rate by 200kcal from size gains, so your 2000kcal/day has gone up to 2200-2600 (average 2400)/day just to maintain weight.
You need to be eating 3-500kcal above maintenance daily (so, in the example, you're now up to 2700-2900 on average) to get 3-5lb gains each month - less than that is inefficient, more than that is probably fat. Furthermore, you need plenty of protein. Rule of thumb is 1g/lb bodyweight/day. So, at 130lb, you need at least 130g protein/day (fortunately, this is not a tall order).
You should be eating plenty of meat, fruit, nuts and vegetables throughout the day. Grains (eg bread, rice, pasta, cereal) are fairly non-essential nutritionally (so why exactly are they at the base of the food pyramid? Probably because the food pyramid is written by agriculturists, not by nutrition experts), but they provide plenty of extra energy, so they'll help you get your calories. Also, drink milk. Lots of it.
I hope this helps you get started. Good luck.