Sue, thanks for including the website. I just looked there, and it’s really good. I have a few helpful books, but the author of the site is better at packing theory into a nutshell.
There’s a lot to know, and even for a non-painters like me, mastering the concepts behind the terms is valuable, even if only to communicate well with other people dealing with color. But learning these concepts has helped me have more success in my work with color with watercolor, ink pads, pencils, markers, and juat picking/planning colors.