Take a look here - no shadowing vs. shadows:
Quite a noticeable difference, right? Want to learn more? Aaaaaahhh, I have the perfect solution to learn some great shadowing tips, try out a few techniques, and even hang out on a live video chat with - oh, look, ME! (how awesome is that?!) -- The Digital Scrapbooker's Guide to Shadowing and Dimensional Effects with Tiffany Tillman?
C'mon, what ya waitin' for? Okay, so fiiiine, you want to try something else, instead - self-paced classes have been on sale for a few days (you knew that, right?!), but you can still grab a discount through today: