Can somebody explain me how Gridded3DSet works?

Im working with an x, y and z coordinate, with a type like this:
   (x, y, z) -> c
I want the x to represent a utm coordinate form 428000 to 452000 with 24 samples. The y will be another utm coordinate from 4463000 to 4487000 with another 24 samples, and the z will represent different levels of height (15) but no a lineal series.

When i define my Gridded3DSet with this:

 public Gridded3DSet(MathType type, float[][] samples, int lengthX,
                     int lengthY, int lengthZ) throws VisADException;

I know the values of lengthX (24), lenghtY (24), and lengthZ (15), but i dont know how to fill the samples array up.

Could somebody help me?

Waiting for your answers. And many thanks...