With Windows 8/8.1 this process was quite difficult and if running Windows 8/8.1, we recommend upgrading before July 29th 2016 to get free upgrade
Now, you can simply open the Settings app, navigate to Personalization > Colors, and activate the “Show color on Start, taskbar, action center, and title bar” option.
You can also choose the color you want to use from the Colors screen.
Simple.