When you bring up the Color Picker, you can click the circle before the L (LAB Color), select a color and use the slider. The color picker also has "warning: out of gamut for printing" which appears as a triangle with a ! inside and "warning: not a web safe color" which appears as a box. By clicking on one or both, it will bring you to the next closest safe color (for printing or web). Also has a "Only Web Colors" checkbox. You can also change the sliders on the Color palette by clicking on the right arrow in the circle and selecting the LAB sliders.