Green is a secondary color that is created by mixing yellow and blue, which are known as primary colors. Depending on how much of each you use, you get what are known as different hues of green. No one "made the color green" it's just naturally there. The way color works is that in the world around us there are what are known as pigments. Millions of little pigments that absorb different colors of the light spectrum. See, light is composed of every color all put together at the same time, and when something has pigments for red, then the red part of light is absorbed by the pigments, so yellow and blue reflect back at the same time, so what you see is green. When something is black, it has all the pigments at the same time, that's why if you wear black clothing on a hot day, you feel hotter, or if you put your hand on a black car on a sunny day, it burns. White simply has no pigments, and therefore all the color is reflected off it at the same time, that's why snow looks so bright, you're seeing all the light from the sun reflecting off it like a gigantic mirror into your eyes. That's why you're supposed to wear tinted goggles when you're in the snow, so you don't damage your eyes.