The monochromatic color scheme uses variations in lightness and saturation of a single color. It looks clean and elegant. [...] The monochromatic color scheme is perfect for our task of generating CSS via PHP based on forming shades of a base color.

You'll need to grab their library to work with in the tutorial, the rest is included in the tutorial. They show how the CSS is defined, how to use the CSS in your page and some sample screenshots of the resulting layouts with the monocromatic coloring.