Looking at the core of your code, we see:

background(0);
float ruido = in.mix.level()*600;
x=x+in.mix.level()*100;
fill(255,255,255);
Now the first line draws a totally black background. So far so good.

The second line creates a variable and assigns it a value.
This variable isn't used anywhere else, which makes the second line do nothing.

The value of x is updated continuously by the third line, based on the previous value and the value returned from in.mix.level(). Since (I assume) the value returned from that function varies only between 0 and 1, the value of x is going to keep increasing.

The fourth line makes it a white square.

The last line draws a square at some x and y position.


So the real question is, what values of x and y do you want to use?
How should the square move in relation to the incoming audio?
As it stands right now, y is never even updated, and x only increases.
This explains why your square does nothing except move to the right!