Brightness and Contrast: Use the sliding scales to adjust how bright or dark a photo can get. Try adjusting both to achieve the perfect mix of brighter highlights and darker contrasting colors. 

Color Balance: Move the different color tabs around to intensify the Reds, Blues and Greens. For more of that color, slide to the right, for less slide to the left. 
 
Levels: Try adjusting the three tabs underneath the color peaks. Moving the Black, Gray and White tabs into the different peak areas will make those areas (dark, mid tone and light) more vibrant. This tool can have the most dramatic effect on a picture! 

Dodge and Burn: For areas needing lightening and/or darkening, adjust your brush size (top left of the screen) and draw over an area to diminish the effect of light glare or a dark spot of the photo.