If you are trying to create a Bootable USB Windows Installer? They are simple to make but depending on the USB Flash Drive in your possession, you may have trouble creating it so your best option is to utilize DISKPART from the Command Prompt. Unfortunately, while preparing the USB for the 25-minute upload of the uncompressed ISO image to your USB using DISKPART, you get a message telling you that you can not mark a USB Flash Drive as active and that is due to your USB drive being GPT instead of MBR.
Here is my method to create a Bootable USB Windows Installer.
01. Open the Command Prompt
02. Type DISKPART and press enter.
03. Type LIST DISK and wait for it to detect the USB.
04. Type SELECT DISK 1 (should match your USB) and press enter.
05. Type CLEAN and let it erase all the contents.
06. Type CREATE MBR and press enter.
07. Type CREATE PARTITION PRIMARY and press enter.
08. Type SELECT PART 1 and press enter.
09. Type FORMAT QUICK and press enter.
10. Type ACTIVE and press enter.
You can now use Windows Explorer (in Windows 8 and later) to see the contents of your ISO so that you can copy it to your USB Flash Drive. If you are using any versions of Windows 7 system, you will need to install additional software that can read the contents of an ISO file.