I would like to know how to create this shadow effect in photoshop. I know how to make shadow in photoshop but don't know how to make this fading shadow on the left and right side in the image.
One very quick and easy solution would be to ...
Select the brush tool with the hardness value set to zero percent. Click once on an empty layer to get a feathered dot as shown below.
Now, press "ctrl+t" to transform the dot into the desired shape.
Put a shape over the shadow and reduce its opacity to get the result below.