well actually u train the plant by bend it and tying it down so that each hole of the screen has one bud so the are all on top getting the same light..once the plant grows over the screen u pull it back down until all holes are filled usually u only fill bout half then switch to flowering and fill in the rest there is some really good stuff on the boards bout scrog and if u want to learn form the master check out

http://boards.cannabis.com/closet-ca...-ladies-2.html