Problem with background image

[Ed Crossley <ed crossley ntlworld com>]

Hi,
Sorry for this, im a bit new at it all!
I want to set a wallpaper image for my desktop. I go into the Gnome 
Configuration Tool and click on background. I then browse to the image i want 
and select it. Clicking "try" it apears on my desktop. I then click "ok" and 
exit.
I then log-off. Logging-on next time, the image appears temporarily but at 
the point the "Gnome Setup" quits, the default wallpaper appears and mine 
goes! 
Why is this? Can a do ANYTHING to get my image to STAY as the background 
image? 
Thank you for your time, sory to be a pain,

Your friend
Ed