Do you want to know how it's done? Learn how to use Photoshop the easy way!
The first thing you will want to do is to duplicate this layer. Select Layer/Duplicate Layer from the menu bar. Now you will want to select Layer/Layer Style/Blending Options. Select "screen" from the Blend Modes drop down menu.
Immediately you should see a lightened picture. Depending on how dark the picture is, your photo may now be exactly as you want it. This is what I have at this point.
To me this is absolutely amazing. I can now see so much more detail in the grass and trees. I think I will try one more step and see if I can get it a little bit better. The beauty of Photoshop is that if you go too far, you can always undo and go back. I am going to duplicate the newest layer on the top that we just set the "screen" blend mode to.
This looks a little to washed out to me. Somewhere in between this and the last one I am thinking would be good. To get there I will bring the opacity of this layer down.
You can adjust the opacity up and down until you get the picture to look like you want it too. Here is the before and after.