If you buy a kit like I did, it's made by Mother's and cost around $20, it gives you a little sheet on how to go about using it. But basically you spray down a "spray and wipe" wax liquid and then rub the clay around the area that you sprayed. The spray sort of acts like a lubricant I guess and eventually all the impurities will be taken up by the bar and you can move onto the next section. Make sure to do it on a cool surface in the shade.
