First of all, it’s important do understand the meaning of Black Magic. According to Wikipedia, black magic is the branch of magic that is used to perform evil acts or that draws on malevolent powers. I personally think that’s a pretty reasonable explanation of black magic. I would add to it that Black magic is considered a dark art because you use it to get what you want by processes of controlling someone else. But if you are looking into helping someone without hurting someone else, that would be called white magic.
In order to do black magic on someone, you need to awaken the forces of darkness and that could be a serious dangerous move and should not be done carelessly. The threefold law (Wiccan's Rede) states that what you put forth comes back to you threefold. Do you feel so strongly about using black magic to that you're willing to suffer should the magic come back to harm you? Be sure that the outcome you are hoping to obtain is totally worth it.
Most of people still consider black magic to be a mystery, they will never learn true witch craft. It is a science that is spread only to the most devout followers. Not only does it take enough commitment to lay your life on the line just to learn it, it also takes years to learn. Most of the stuff people can find online or elsewhere is child's play, if you want to learn the real stuff you'll have to turn your life upside down and risk everything. Is it really worth it?
On the other hand, a lot of people still believe that black magic is a myth. They consider it to be a psychological or state of mind.
Have anyone experienced black magic before, either as a maker or receiver? I would be so curious to know more about your experiences or your beliefs.