Step One
Okay, this is very easy to do and yet it's very cool. This effect mainly use making layouts and also buttons. Let's get started. Open a image that you want to apply this effect on. Here, I will use a picture from the movie Matrix.
Step Two
Select the area that you want to put the Back light effect using any of the selection tools. In this case, I used Rectangular Marquee Tool(M).
Step Three
Create a new layer (Shift+Ctrl+N) and using the Paint Bucket Tool(G) fill the select area with your chosen color. Most people use black or white in this case. But you are welcome to use any colors you wish to use, I guess.
Step Four
Now this is the important part. In the Layer Palette, decrease the Opacity of the Layer 2 to whatever you like. It's usually 30%-70%. And guess what! You've done it! Wasn't that easy?
Here's what I came up with,
