There are many training books available for Photoshop, those for the new CS version are just arriving. Frankly, you'll need at least one, probably several. The in-the-box 'documentation' for Photoshop is pretty meager. Some of these books are step-by-step, hand holding instructions and some are more generous in why and how the steps are taken. Understand how colour theory works, Fake the look of infrared film, and also Free CD with photos & more
1. Photoshop Creative book