Confusion installing windows via DVD/ISO
I've tried to follow the instructions here How to install Windows using Boot Camp - Apple Support to install Windows 10.
The instructions state that I should create an ISO file
When you purchase Windows, it comes as a disk image file (ISO) that you download, or as an installation disc or USB flash drive. If your copy of Windows came on a DVD, you should create a disk image of it to work with Boot Camp. If your version of Windows came on a USB flash drive, you can download an ISO from Microsoft
But when you run bootcamp, it says "The installer disc could not be found". I have tried with the ISO mounted, I have installed the ISO onto a bootable USB and that mounted and unmounted. Neither work. The instructions linked above make no mention about this at all. What is going on?
iMac, OS X El Capitan (10.11.1)