Learn Photoshop CS4: Getting Started 06: Adjusting Colors  

Learn Photoshop CS4: Getting Started 05: Working with layers    

Learn Photoshop CS4: Getting Started 04: Selecting portions of an image  

Learn Photoshop CS4: Getting Started 03: Retouching blemishes  

Learn Photoshop CS4: Getting Started 02: Brightness and Contrast

Learn Photoshop CS4: Getting Started 01: Getting Photos From a Camera