Downloaded source images from http://fx.worth1000.com/tutorials/161386/lighting-a-giant-elephant
using polygon lasso tool, cut out the elephant image, and duplicate the image to make 'shadow' and 'light' layer to make light effects.
Shadow
light
To remove shadow layer, add vector mask on the shadow layer which should be above the light layer
Select the mask, and using the brush tool, remove the shadow layer's image. Make sure that before erase it reduce the brush tool's opacity for smoothness.
To create the shadow of the elephant, pick the color of the shadow of cars, which is dark blue.
And using the brush tool draw shadow carefully, and change the layer's type to multiply.
And using the bright and contrast tool and the color balance tool, adjust its color to the same color of the cars' shadow.
Final Result
Tutorial link : http://fx.worth1000.com/tutorials/161386/lighting-a-giant-elephant