Down load the blackshouldered kite if you want to make some layers to learn how they work

Click here to download: Blackshouldered kite.jpg

This pdf should also help.

DWJLayerbasics.pdf

1.  Click here: Darkimage.jpg

Use this to work with the layer mode set to “Screen”.  It will lighten the image of somewhat. 

You can also use the Layer Opacity slider to reduce the affect.

Then with a Black Brush, it is possible to reduce the lighening in selected parts of the image.

Here is a second image to lighten just under the dark wing area.

Be careful with the Black Brush and use opacity on the brush of say 30% and go over the area a couple of times to get it just right.

Click here to download: brownfalcon.jpg

2. 2.Multiply mode
   

This mode will enable you to make lighter parts of a scene darker. It also enables some control over how dark, or black the shadows will go.
Here is a practice image. Lighterimage.jpg