well you basically hang a screen above your plants and then train the plant to grow into a bush underneath it. It increases your bud sites and yield, as well as keep its height to a minimum, but its a pain in the ass to do. JustASeed has an amazing ScrOG grow called "Lovely Ladies". Check that out, and for a detailed description on it look at the FAQs...or ask more specific questions if you cant find it there.

Crime.