You move a small cursor from the center of the circle to achieve the color balance you like best. The rainbow arrow is return to original color. This screen capture shows the tone control slider tools. Left is mid tones. Top right is high light.
Bottom right is the shadow control.
The question mark is a help menu. The square window inside the preview shows the effect as long as you hold the mouse on the slider. As soon as you release the mouse button the whole image changes. This preview area is moveable. The small wrench is the tool box.