Changing Login Window theme for Ubuntu

Step1:Right click in the desktop ->select change background -> click on get more backgrounds online.

 - This link provides you the themes to download for "Login Window".

 -It will be in '.tar.gz' extension

 -Eg: GDM-SoftFlowerGdm.tar.gz

 Step2: 

 Open Login Window manager at System–>Administration–>Login Window

Click on the Local tab, there are some themes in the selection box

 Add the downloaded themes by clicking Add,then locate to the file and install, or just drag

and drop the downloaded theme package into the themes selection box. 

--And thats it.You can now restart and feel the new appearance of your login window!!!

Change Login window theme in Ubuntu 9.10/10.04 and higher  
-To change login appearance in Ubuntu 9.10 and higher version becomes inconvenient.Fortunately,there are two GUI tools I found that could instead to accomplish this task.

Step1:  -GDM2Setup,a GUI tool designed to configure login screen behavior.It can be installed by typing the following commands in Applications->Accessories->Terminal 

$ sudo add-apt-repository ppa:gdm2setup/gdm2setup

$ sudo apt-get update 

$ sudo apt-get install python-gdm2setup

 Step2: 

 Launch GDM2Setup from System->Administration->Login Screen(GDM2Setup),

change Login screen background in Wallpaper tab.

 Step 3:

- In order to select the images, you need to place the images in the root desktop.

-To go to root desktop type the following command in terminal

  $sudo nautilus

 -A window will be opened which is the root.You can edit the files in the root 

if you access them through this command.

-Click the "Desktop" icon.

-You need to save your wallpapers either there or by creating any folders.

-Only then they can be used for the login window.

 Finally you can customize your login window as your wish.

 Enjoy with new settings!!!