I've just gone through the Windows 8 upgrade process, and I am at the "Install now/Install by creating media/Install later from your desktop" stage.

I've already got a sufficiantly big, empty partition, so can someone explain in fairly simple terms how to install onto the new partition?

I would prefer not to burn the ISO onto a disk, it would be a lot easier if I could use a USB drive.

(I've done quite a bit of googling, but all that I can find goes into endless detain about the partitioning, and spends very little time on putting the ISO on a booteable drive. How do I do this? Do I need to empty the drive? etc?)