How to change color of window background?

My eyes are tired of staring at bright and shining fields of white windows all day.

I really want to change the color to black or gray. (For example, My Computer, Start Menu, File Explorer, etc are all in white background color)

Is there any way to change this? I've been digging the internet for a solution, and I can't find one.

Welcome to the Seven Forums
You are going to need a custom theme to do what you want to do, my personal favorite is charleston2378's deviantART gallery it's a very nice dark theme.
You will need to do 1 of these 2 ways of Enabling custom themes for it to work.
http://www.sevenforums.com/tutorials/34579-enabling-custom-themes-windows-7-a.html
Or
http://www.sevenforums.com/tutorials/28377-theme-how-apply-custom-themes.html?filter
Here are two screenshots as an example, I have changed many system files to achieve that exact look but you do not need to to get the basic look.
If you need any help installing a custom theme let me know.
Jerry