Select next the following tool to represent the layer of deepness on the upper part of the button.

Create Design Studio Web Layout in Photoshop CS

Create Design Studio Web Layout in Photoshop CS

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

Create Design Studio Web Layout in Photoshop CS

Gradient?s parameters:

Create Design Studio Web Layout in Photoshop CS

Take the same instrument and represent one more layer on the recently made one.

Create Design Studio Web Layout in Photoshop CS