First off, read my “Youth Gone Wild” article way back in issue #68 of T-mag. That will get you started with the basics. The “Dawg School” articles will help too.
Since we don’t know much about how you’ve been training or eating, here are some basic tips: For strength, train in the lower rep ranges where you go heavy enough so that you can only get 1 to 5 reps. As for supplements, all you need at your age is FOOD and lots of it. Don’t skip meals and be sure to eat plenty of protein. If you must use a supplement, get an MRP protein powder concoction and drink one after you train or whenever you would otherwise have to skip a meal. Throw in a multivitamin, too. That’s it. That’s all you need. The rest lies in food and proper training. Go through our previous issues section and start absorbing everything you can.