By now it's also possible to install 64 bit systems within Virtual Box - as long as your computer is ready for that. But what if that's the case and you still don't see any option listed to create such a machine?
I can give you two things to check in order to solve that:
First: Go to BIOS/UEFI and check if the virtualization technology is activated. Easy, but often forgotten.
Second, check if no other Virtual Machine software is blocking Virtual Box - for example HyperV. If that's the case and you don't even need HyperV (which is included in Windows 10), remove it by going to Programs and Features.
A reboot is possibly necessary, but afterwards you can start Virtual Box, create a new VM and see also see 64 bit versions in your selection.
No matter how often you try to press F2, F6, F8, F12 or anything: If you have a pre-installed Windows 10 you need to change some settings in the BIOS/UEFI in order to be able to boot from your DVD.
First, you need to get into the BIOS/UEFI menu to change the boot order by pressing Fn+F2. As you directly notice you can't even see the DVD drive.
In the following you should select 'Boot Mode' and chose 'Legacy Support' instead of 'UEFI'.
And in 'Boot Priority' you should also change from 'UEFI First' to 'Legacy First'.
Go to 'Exit Saving Changes' and open the BIOS again. Now you can see a bit more and also the DVD drive like you were used to in the older days.
Finally you should put the DVD in the first position ahead of the HDD. Save the changes and your inserted DVD will boot.
You'll be able now to install Windows 7, 8, 10 or anything from your DVD drive.
