How do good artists get good?

I am 14 and a terrible drawer. I just had an urge to start drawing and get really good at it but I stink. I don't know how shading works, I cannot envision images in my head, when I close my eyes all I see is black, my mom says I'm logical, un-creative, and an auditory learner, and I don't know where to start or how. Please help.