You can't
You power up to high tension, (when your energy bar is blue), and then you push the R3 button.
raging blast is a different game than other dbz games you don't find the dragon balls you get them in super battle trial if you do well
you have to enter single player and it will say shenron at the bottom.
the dragon balls if you colect 7 you get to call the dragon and get a wish PS they give you choices