You can also improve your photos by using adjustment layers. Open the photo that you want to edit in Photoshop Elements. In the menu, choose Layer, New Adjustment Layer, and note your options.
To adjust your photo's exposure, you can use Levels (which lets you make histogram adjustments) or Brightness/Contrast. But you have other options as well. Want to change the color saturation, or even bleach your photo so that it becomes a nearly monochromatic image? Try Hue/Saturation.