In the Reframing Photography book, Editing describes:

how to change image tone and contrast in the darkroom or digitally,
how to digitally correct color casts,
and how to retouch photos to correct for flaws.

Captured data is raw material. By seeing your image as malleable in form and meaning, you can change the content by selecting parts of the image, through reconstructions of collage with the tools of the darkroom, the xacto knife, digital cut and paste, and by incorporating type with imagery. The book provides step by step instructions for all sorts of collage methods, and special techniques for working with type and image including how to create type to fit around or within imagery, and how to fill type with photographs.

Website resources expand on these descriptions by describing ways to correct image contrast and color casts in the darkroom, to make digital color corrections with Adobe Photoshop's Variations, to crete a digital duotone, and to retouch red eye. You can also learn digital or darkroom variations of the special printing techniques: brulée (burning negatives), solarization, and double exposure. Finally, we continue to look at collage methods with darkroom combination printing.