How to use Landscape Layer Sample node?

Hello. As far as I know, Landscape Layer Sample node samples a landscape layer with values from 0 to 1.
My goal is simple: tweak these values to add noise in order to improve the blending among layers.
The problem: I don’t know how to use it, except in combination with the grass node, because I don’t know where to output the Result of my noise function.
Here a simple screenshot:

So, how can I use this node?
Thanks in advance!