1. Prepare image (JPEG) you would like to use no more than 256 KB in size
2. Type regedit in the Search program and files and press Enter to open the Registry Editor.
3. Located the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background
4. Double click on OEMBackground and set the value as 1
5. Copy your image file which you are going to use as the login background to the following location:
%windir%\System32\oobe\info\backgrounds
6. Rename the image file in %windir%\System32\oobe\info\backgrounds as backgroundDefault.jpg
7. Press Ctrl + Alt + Del to check your background image