This video will take you through the process of hand stretching (opening) pizza dough. Using this method, the pizza dough will stretch naturally, making for a more even crust that's less likely to tear.
When stretching pizza dough, you should never use a rolling pin, as it will push out all the gas, negatively effecting oven spring and resulting in a condensed, tough texture.
The Basic Approach to Stretching Pizza Dough