First drag the bar on the "Hue" selector to the area of your colour palate.
Now click inside the Brightness/Saturation area and drag to the colour share until you reach to your desired colour.
"Swatch" bar will show you the final colour result.
The hexadeciaml colour code will be generated in the "Hex" box.
Simply copy the codeit where you want to use it (i.e. #0000FF).