To use the pipette go to "pages" -> "design" and click the "primary color" dot. What you see from here may differ depending on the web browser. In Chrome, for example, the round color palette will show, but in Safari you first have to click the button, "show colors", at the bottom of the window.
Select the pipette icon and extract the color you want from anywhere. Make sure to downsize the window a bit and keep the source of the color visible, for example a separate window. The pipette will automatically generate the color and hex code next to the ”primary color”dot.