Go to Window -> Run (Shortcut Window Button + R)
Type REGEDIT and hit Run.

Navigate to the following folder.
HKEY_LOCAL_MACHINE\Software\Microsoft/Windows/CurrentVersion/Authentication/LogonUI/Background

You should see a DWORD, OEMBackground. If not, create a new DWORD (32-bit) value with the name, OEMBackground

Once created, double click it, Keep Base as Hexadecimal, and update "Value data" to 1. Click OK.

Close the Registry.

Now, open Windows Explorer and navigate to the folder, C:\Windows\System32\oobe\info\backgrounds\

Add the jpg file that you wanted to be your welcome screen here. Please make sure that the file size is below 256 kb.


Rename the file to "backgroundDefault.jpg".

Close the Window...

You are done! :-)