Unfortunately, most people on this site will not take the risk. According to United States federal law, we cannot actually take a minor as a student. For more information on this, please refer to: http://www.spellsofmagic.com/read_post.html?post=462285
Even if you did post your age, most will not take the risk of you lying about your age because we can still be held liable even if you lie. What we can do is refer you to books we have found in the past that may be helpful. For dark magick, I would suggest starting with Nocturnal Witchcraft by Konstantinos. Its not full on black magick, but it is a good place to get started.
I hope this is helpful.