1. Download above tool
2. run (may have to choose "for installation on other PC" or similar so you can burn the image to DVD. I forget exactly.)
3. ISO will download, then burn to DVD.
To upgrade:
Option #1 - insert DVD with Windows running and start "setup.exe" the follow instructions for a clean or upgrade installation, or
Option #2 - use a blank drive (i.e. new SSD or format old drive), unhook other drives to be safe, then BOOT to the DVD and start the installation.
*NOTE* - do NOT put in a key during installation since it's for a PC with an activated W8.1 already (even with the blank drive it's fine). This will be handled automatically. So just SKIP that option.