Help smoothe/add shadow to my character?

[Audrey]

I know that this wasn't taken by a fancy camera or an actual camera at that. But I was wondering if someone could help me add a shadow to this Sims 3 photo I took. It would be much appreciate. Just a simple shadow behind/on/around the girl, please. :]

I posted this in another section but thought here might be a bit more appropriate?
If this isn't allowed, please tell me and I apologize.

Link since it resized: http://i45.tinypic.com/fnhedd.png

This image has been resized. Click this bar to view the full image. The original image is sized 1105x847.