The fifth and last section of the Tools palette allows you to set colors and holds the active colors associated to the current image. It contains a large rectangle that show the current active color and six rectangles below which can be used to hold different colors for later use. The active color is the color used by all tools the use a color such as the brush, line, draw tools, etc. The large rectangle referred to as "Set main color" when clicked on produces as palette of colors. You select the color you wish using the ring of colors which is further defined by the box within the ring or you can select your color by using the three slider bars below. You also have four options on the top HSL (the default), RGB, WEB, and IMG.
To move the selected color, just click on one of the six rectangles below. The active color, i.e. large rectangle turns white. To make a color active merely click on the desired rectangle and it will move to the active color rectangle.