If you want to concentrate on photo editing and retouching:

• See Edit images with ease for an introduction to the Photoshop image-editing features.
• See Using the File Browser (Photoshop) to find out how to quickly inspect files before opening them in Photoshop.
• See Using the healing brush tool (Photoshop) to learn how to remove flaws effortlessly while preserving tonality and texture.
• See Making color adjustments to learn how to fine-tune the color and tonality in your photographs.
• See Creating multiple-image layouts (Photoshop) to find out how to quickly create contact sheets and customized photo pages.