How to create the effect shown in the attached picture in Photoshop?

Question

How can I create the effect illustrated in the attached picture? If a box of a given width (say 300px) and of the same height and color as in the picture is inserted in the middle, the resulting picture will look bent with shadow at both the right and left hand side.

I highly appreciate it if the instructions are given in more details as I am new to Photoshop.

I am using Photoshop CS6.

Answer 1

New layer - draw a black to transparent gradient.

Choose Edit > Free Transform

Hold down the Command-Option-Shift Keys (Mac) or Ctrl-Alt-Shift (Win) and drag a top corner inward.

Hit OK

Choose Edit > Free Transform again, hold down the Option/Alt key and drag the sides in.

Duplicate layer and rotate 180° and place at bottom of image.

Draw a line with the same color as the background. and place it above the gradients.

Select both Gradient layers and merge them.

Adjust sizing if needed.

Finter > Blur > Gaussian Blur to your liking.

Lower opacity of gradients as needed.