Process order

I would like to dual boot a Win7 system and add Win10. I have created a partition for Win 10 and have a full version DVD of Win 10 with product key. I started to run the DVD and completed all the info Win 10 was asking me. However, I was not asked to designate which partition (drive letter) I wanted to install Win 10 too as it started installing files. I aborted the install as I did not know if it was over writing my Win7 install, which I did not want to happen. Would I have been asked which partition to install it too AFTER all files have been installed or was it in the process of simply overwriting Win7?

Thanks

You need to boot the computer from the DVD and select the Custom Install option. When you run setup.exe from within Windows 7, it is going to upgrade the Windows 7 to Windows 10.

OK, and thanks. I booted from the Win10 DVD and selected the Custom Install for the partition I created. I entered my product key and then was greeted by the error message"Windows can not be installed in the selected partition. It is GBT", or something close to that. I'm assuming it has to be MBR instead of GBT. Is there a utility to accomplish this?

You have to boot the DVD in UEFI mode. From the UEFI firmware boot override menu, select the DVD option that had UEFI in front of it.