Lighten or Darken
You can adjust photos that are too dark or too light. The Brightness/Contrast option is just like adjusting your computer monitor or TV; move the slider one way to darken it, the other to make it lighten it. Once it looks correct, click the OK box.
You should be able to ‘preview’ your result. At this stage you are affecting the whole image, not just a portion or selection. To do that you need more specialised selection tools.
An ‘Auto correction’, or ‘Autofix’ button is a handy feature. This automatically looks at the values on the photo and applies corrections for you. | 
