Change Logon screen in Windows 7

STEPS to change Logon Screen :-

1-Open up your run command. (Fastest way to do is to do 'Windows Key' + r)

2-Type in regedit.

3-Find HKEY_LOCAL_MACHINE > Software> Microsoft > Windows >
   CurrentVersion > Authentication > LogonUI > Background
   Double-click on OEMBackground



4-Change this value to 1. 

5- Click Okay and close out of regedit.

6-Open up Windows Explorer or My Computer and navigate to your
Windows directory.

7-In your system32 folder in your windows directory, you'll need to create a couple new folders. For the standard user,  go to c:\windows\system32\oobe and create a folder labeled info.
 Inside the info folder, make another folder called backgrounds.

8-Your final path should look like
 c:\windows\system32\oobe\info\backgrounds

9-Place your image in this folder. Your file must be labeled backgroundDefault.jpg