Color selectors

[Brendan Scott]

Hi
Is there anywhere which explains the point of the various color selector dockers?

I am a little confused about the artistic color selector.
I get that it's hue around the outside, saturation radiating in/out and lightness on the side. What I don't get is the point of rotating the wheel. I'd like to pick a color and have the closest color on the wheel selected (so that I can, for example, choose its complementary). Even a grid reference would be helpful, since I keep forgetting.

Thanks