iMac 2010 High Sierra

I am having real difficulty installing Windows 7 through Bootcamp assistant 6.1.0

I have a Windows 7 OEM installation DVD. I have downloaded the latest support software (the first box selected) in the assistant. However, when I run Bootcamp assistant to "Install Windows 7 or Windows 8" (the second box selected) it says "The Installer disc could not be found" - inserting the disc before or after this makes no difference the disc keeps trying to load and Bootcamp assistant never moves on to the next step to create a partition.

Any help much appreciated.

iMac (27-inch, mid-2010) macOS High Sierra Version 10.13.6