Drag the color sliders. By default, the slider colors change as you drag. You can turn off this feature to improve performance by deselecting Dynamic Color Sliders in the General section of the Preferences dialog box.
Enter values next to the color sliders.
Click the color selection box, choose a color using the color picker and click OK.
Position the pointer over the color ramp (the pointer becomes the eyedropper), and click to sample a color. Alt-click to apply the sample to the non-active color selection box.