You are young, so this is going to be easier for you now then any time in the future.
Come here daily, and read everything you can. Knowledge is power. Don't be afraid to keep asking questions.
The link above posted by orion is really good. Try to read all the links there. (I know, that vroom guy is hard to look at with how ugly he is, but the post is really good.)
There is a link there to the 7 habits of highly effective diets. I believe that can be the most important information for you right now.
This is the link directly to the 7 habits article, but still go to all the other articles. Eating right is the most important thing. I don't think you should be too worried about trying to go on any real diet other then that, and may find that as long as you are working out and eating right, that most likely will be enough.
Just make sure it is a new lifestyle choice, not just a quick fix you dump the second you hit your goals.
You will notice that article does not expect perfection, and actually allows for times to eat foods that are not good for you. That helps keep you on track. Just don't overdo it.
Another thing about this is don't expect to be perfect overnight. Just try to keep improving all the time. And setbacks are perfectly normal. Don't use them as an excuse to quit.
Important: Do not skip meals, especially breakfast. Sumo wrestlers specifically skip breakfast and lunch to keep their metabolism down so they can get fatter. Try not to be a Sumo. Skipping meals is a big mistake.
Keep records of everything you eat, and all the exercises you do. We can be of better help to you if we know what you are doing. So far we have too little knowledge of your classes, and your exercises. It is possible to overdo it, and it is also possible to underdo it.
Overdoing it can actually stall the results, and cause you to burn out. Starting out slow and small is perfectly fine. It will set the stage for later. Learning to lift correctly is more important them just moving weight. Once your form is good, then focus on the weight.
Finally do not rely on the scale. It is not the best tool by itself. Pictures of yourself and the mirror are two of the best tools you can use. The picture will show where you started, and the mirror will show where you are at.
The scale may show increases or decreases in weight, but it will not say if that is muscle, fat, or water weight. You could also use a tape measure and measure your body parts, but make sure you do this no more then once a week. Every other week may actually be better.