ok i think i can explain it.
The basic part is a displacement shader, that goes into compute terrain.
On the function input of the displacement shader attach a Perlin 3D scalar. On the input of that attach a Multiply vector. Multiply vector has 2 inputs. On one is a "Get position", and on the other is a "Constant vector". My XYZ values for the Constant vector are 0.7,3,3. That's prettymuch it, then I added a terrain to the input of the Displacement shader. Oh and the Displacement shader displacement multiplier value is set to 0.15. I also added very small stones of a slightly different colour to give texture to the sand, and currently am rendering an updated version with more small scale ripples in the sand (added another displacement shader that has a build vector)