Well I tried and I cannot figure out how to put my user picture in that box. It always stays white , help me fix this please.
Here is a screenshot:

Do you have the Windows XP logon enabled?

Define windows logon exactly..

 
I think you don`t use this login-screen, then XP don`t show a userpicture.
 
Enable the login-screen or use another visual-style without the userpicture in the startmenue.
 
You can use other Visual-Styles, VS are here, here or here.
 
Read this tutorial to change your VS

Can you tell me how to enable login-screen? Or link me to a thread that explains?

 
Here you go: http://www.pchell.com/support/welcomescreen.shtml
 

Thanks