We could spend the entire semester on digital darkroom approaches - but we won't. There's so much technology available in manipulating pixels, chroma and luminance that we'll leave it up to the Photo Shop gurus to teach.
Instead I want to give you a simple overview of basic tools you probably have in whatever photo-manipulation software that shipped with your laptop. If you have a Mac, for example, you have iPhoto. If you don't have photo editing software, there are some programs you can download.
iPhoto uses basic and powerful tools in their editing software: Exposure, Contrast, Brightness, Saturation, Temperature, Tint, Sharpness, and Straighten. The following images show differences in using combinations of these tools:
Consider Camera+ as a digital darkroom alternative.
