Shooting with power is important if you want to be able to score from more than about 10 yards out. So what allows you to strike a ball in a way that goalkeepers will fear you? 2 things: physical strength (specifically your core and your quads) and technique.

Check out this video with great soccer-specific core strengthening exercises.

And this one for some examples of the technique of shooting with power, as well as to learn a little German.