The concept behind controlled throwing is to start by setting the dice in a specific manner, then gripping them and throwing them the same way each time. This produces a "controlled throw". The desired result is to alter the random outcome of the two dice when they land. You are trying to skew the sevens to roll ratio so the seven comes up less times than with a random throw.
The first element of dice control is setting the dice. There are some sets that will produce different outcomes if the dice stay on axis. Here are the most popular dice sets used by controlled shooters.