if you get bored from your start screen you can change it easily by ModernBack Changer.

Download Free Windows 8 Start Screen Background Changer

ModernBack Changer is free tool, allows you to change background and accent color of the immersive start screen in Windows 8.

For the background you can select a custom one by selecting your own image.

You may wanna see this video tutorial


You must run the tool as administer