Open a new file with 766×400 px and 72 dpi. It must be painted after that with this shown color – 424242.

Take now this tool to represent the lowest layer of the central site’s panel.

Fill 0% on the layers.
Blending Options-Drop Shadow

Blending Options-Gradient Overlay

Gradient’s parameters:

Take now an appropriate fragment of the picture and place it exactly the same way you may see in the following picture.