Install Windows to VHD

Step 1, Boot your computer using your Bootable Media (DVD or USB media)

Step 2, At the Install screen, press SHIFT+F10 to access the Command Window.

Step 3, Run diskpart command and type the following command:

 list disk.
 select disk 0 (where 0 is the disk number)
 clean.
      (CAUTION:This will remove all partitions on the selected disk causing data lost.)
 convert gpt.
 create partition efi size=512
 create partition primary size=40960
 format fs=NTFS quick.
 assign letter=W
 
 Then type exit to completed diskpart

Step 4, Type mkdir w:\vdisk

Step 5, Run diskpart command again with below commands

 create vdisk file=”w:\vdisk\windows10.vhdx” maximum=25600 type=fixed
 attach vdisk
 exit

Step 6, exit the command window and click install now with "Custom: Install Windows only" and selct the vdisk just attached.

Step 7, Windows is now installing the operating system.