The main window

1. The picker panel is the entire panel inside the window. You begin your color selection by clicking and holding the mouse button anywhere inside this panel. After that you simply drag the mouse to wherever you want on the screen to grab the underlying color. Note that when the mouse cursor lies in the window after the drag has been initiated, the window will automatically move out of the way to allow you to select any color underneeth it.
2. The color preview panel is the top half of the picker panel. Here you get a live view of the color under the mouse cursor and also the color code. After you release the mouse the current color is copied to the clipboard and whilst it's stored there you also get a message informing you that you can simply paste the color code.
3. The live preview panel is the bottom hald of the picker panel. Here you get a live view of the immediate area under the mouse cursor slightly zoomed in so you can make delicate selections.