Changing the logon screen in windows

      1)     Open regedit  

     2)    Right click on HKEY_LOCAL_MACHINE and select find

     3)    Search for OEMBACKGROUND

     4)    Change the value as 0 to 1

     5)    Open gpedit.msc

     6)    Go to computer configuration\administrative templates\system\logon

     7)    Enable the “always use custom logon background”

     8)    Go to c:\windows\system32\oobe

     9)    Create new folder and name it as info, get inside

   10)  Create another folder and name it as background

   11)   Paste jpg file inside and rename as it backgroundDefault.jpg

   12)  Image should be within 256 KB

Note: No need to reboot just Win+L

Or

Download the third party application “Windows Logon Background Changer”