Help in the tool Darcy Flow

I have a problem. I want to use the tool Darcy flow and have no raster.
Now I want to create an artificial landscape with imaginary values​​.

How to create the input raster for
- effective for mation porosity raster,
- saturaed thickness raster and
- formation transmissivity raster?

With a spline interpolation, I could create a raster, but how do I assign the raster then the porosity?

Can you help me with my problem?