Photoshop Lighting Effects
Photoshop is best used to enhance existing lighting, fixing mistakes, and improving things, but it is not a replacement for lighting in the studio.
Generally you can put an accent in, but it's not going to turn a flatly-lit picture into a well-lit picture.
Sorry, photography is expensive. You're better off spending the licensing fee for photoshop on an Alien Bee (or even a Yoguno) and some modifiers.