How do you get Sonic to turn to super Sonic

You must collect whatever the 7 things are in the game (usually the Chaos Emeralds). In the earlier games and the sonic Rush series you collected them via a minigame found somewhere in the stage (look for the really big ring/spring or the red ball) once you complete the minigame you get the Emerald.
In sonic adventure and such, you get them after a stage or at certain plot points. then you can usually change into super sonic or one of his many different forms.

For sonic, they are always the chaos emeralds. you find them as you pregress through a certain game. In the comics, you needed 100 magic rings and 7 chaos emeralds, (which in the comics there were tons of) but in the real sonic world, there are only 7, and you dont need 100 rings to go super.
You can only turn into Super Sonic in the extra zone if you are playing sonic advance.