Light ― Science & Magic: An Introduction to Photographic Lighting

You don't need equipment, you need knowledge. You need to understand what light is, in order to soften it, direct it, shape it. This was the textbook we used in my photo lighting class. https://www.amazon.com/Light-Science-Magic-Introduction-Photographic/dp/0367860279 After you understand light, you can make do with whatever sheet of paper, foil, or window is around you.