Installing Windows 8 operating system from a USB flash drive is very common for Netpad, tablets because it has no optical drives like CD or DVD ROM.
To install Windows 8 from USB flash drive you will need a DVD of Windows 8 operating system and coping those files into USB flash drive will not work. So you need a ISO file of Windows 8. You can download the ISO file from the internet. Many people upload it in many file sharing website or you can make an ISO file of your Windows 8.
1. A 4 GB USB flash drive for 32 bit windows and 8 GB USB flash drive for 64 bit windows.
2. A DVD of Windows 8 or 8.1 or 8.2 or ISO file.
3. A computer running with windows7, vista, XP or Windows 8.
If you already have the ISO file then download the Windows 7 USB/DVD download tool and install it. It is a software with 2.5MB Size.
After installation open the software and 'Click Browse' and select your ISO file and follow the next steps.
Select your USB flash drive and follow the steps and it will start coping ISO files to the flash drive and few minutes later it will be completed and your flash drive is now ready and it will be a bootable windows 8 and you can install windows from it now.