you'll need:
- USB Flash drive (I recommend 8GB)
-Windows 8.1 .iso image and media creation tool (both obtained from here:
http://windows.microsoft.com/en-us/windows-8/create-reset-refresh-media just click Create Media)
- Keyfinder since you'll not go far with the installation without the proper CD key from you Windows 8 that you are running now ( Download from here and just follow the steps, it will show you a list with Windows detail, you just need CD Key https://www.magicaljellybean.com/keyfinder/ )
INSTALLATION
1. Write down the CD Key
2. Run the program that you've downloaded from the Microsoft site (it will prepare the USB and download OS)
3. Turn off your PC (backup anything important)
4. Enter Boot Menu (usually F11 key, but...