How to change the windows 7 logon back ground

Open the run dialog box (that’s the Winkey+R) and type in gpedit.msc and hit
OK -> This will open up your Local Group Policy Editor -> You then want
to go to Computer Configuration\Administrative Templates\System\Logon ->
Then double click on Always Use Custom Logo -> The next thing you want
to do is choose enable in the new window that pops up -> then click Ok
to close the window. ->Then close Local Group Policy Editor.

For Window 7 Home Premium
"up the run dialog (Winkey+R) and type in regedit and hit Ok -> Now
"
navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Authentication\LogonUI\Background -> Double click on
OEMBackground and in the box that pops up, change its value to 1 and
hit Ok -> Now navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\ -> . Right click on Windows , now choose New-> Key
and name it System. (sometimes this key may already exists, if it does,
skip to page 3.) -> In the white panel on the right, Right click and choose
New->DWORD (32-bit) value and rename it to OEMBackground -> Now
double click on UseOEMBackground and change its value to 1 -> Now exit
your registry editor and go to page 3 for the final step