Fill 0% on the layers.
Blending Options-Gradient Overlay

Gradient?s parameters:

Make three copies of this new made layer and make them smaller, using
the same option we applied earlier.

Select the same tool to create one more layer, reserved for the volume.

Blending Options-Gradient Overlay

Gradient?s parameters:

Make three copies of this new made layer and make them smaller, using

Select the same tool to create one more layer, reserved for the volume.
