To make shaded hair on a skin, you first need to go onto miners need new shoes skin website. When you are ready to make your hair, Just Click on the two diagnol squares button and choose a color. Now you are free to draw! 
 But, to make it on the skindex or on another website, you slowly slide the color skider up and down. This is also possible on Miners Need New Shoes, but i think the first option is better.