if enabled use the middle multi-color scroll bar to scroll up or down to the color you want. If you want to select the shade of color, click the shade you want in the large shade box. Finally, the color code will appear in the bottom-right corner # box. If you want to keep that color, click the text boxes below the color picker and then select the color and then click the alternate box to begin with a new color.
The above HTML color code picker is using code from the YUI Color Picker script.