My picture was lighted by an early morning sun, I had to think to the way to add some shadows from the balustrade to the ground on the foreground. Here is the way I used and I hope it will be useful for you.
1. COPY AND PASTE on a new layer the balustrade (or any object you want to project the shadow).
Then place the copy just under the original layer, using the Free Transform tool.
2. CHANGE IT INTO A BLACK SILHOUETTE
Using the Image > Adjustments > Brightness Contrast setting, as shown below (Brightness minimum, Contrast maximum).
3. TRACE SOME DIRECTIONAL LINES FROM THE LIGHT SOURCE
Choose the light source (