How on earth do you get a color into the color picker

In the properties bar. In the Bg box i've got color

#E9E6F2

I want play around with this color and darken this color slightly. so i
click on the box next to it, brings up the color box.

Go to the top right button ' system color picker' select it and it brings
up the second color box - but for some reason this defaults to white!

How are you supposed to get the color you're working with in there if you
dont know the Hue, Sat and Lum codes!!

It's bloody ridiculous!