The others will be sick of my saying this, but...
- eat LOTS of fresh fruit and vegies
- eat LOTS of nuts and beans
- eat SOME meat, fish or dairy each day
- if you want to get bigger, eat LOTS of starchy stuff (bread, pasta, spuds, rice)
- make a workout drink - 500ml milk, 3 eggs, 100g skim milk powder; drink half before and half after your workout
Apart from the workout drink, you want to have about 2 hours since your last big meal, not much more nor much less. If you exercise before breakfast, you'll find it very hard because there's no energy in you. If you exercise right after a meal, you'll find it hard because your digestion needs blood to work, your muscles need blood to work, you can't do both - so you'll either tire out easily or throw up.
The workout drink is different because it's a liquid so it can digest really quickly.
As for amounts, since you want to get bigger, if you are
ever hungry then you are not eating enough. You know when you reach that point in a meal and you say, "I've had enough"? Well, keep eating after that. Your body doesn't want to change, so your appetite adjusts to try to keep you the same. When you say, "I've had enough", that's your body saying, "stop eating now and you won't change a bit." You want to change, so keep eating.
You don't need any supplements, at 15 with your hormones that's like being on steroids. No, I'm not kidding. You naturally have a hormone level that 30 year old bodybuilders have to give themselves injections and spend $50,000 a year to get. Make the best of it