Okay, now with v1.0.1, the kinks seem to have been worked out by the Developer (Andr3). That being said, I just wanted to help improve it so others wouldn't have similar issues.
A note to the Developer (Andr3), in v1.0.1, the change once implemented still leaves the application window open instead of quitting. You might want to look into that. Beyond that, it works as advertised.
Looking at the Automator application within NCbackgrounder.app, specifically NChanger, the file being changed is located here on your Mac and you can manually change it:
You will need Admin privileges and I don't suggest the general user to the change themselves; just letting you know where the file being changed is. You do have to name the tiff you're moving to "linen.tiff" from what I can tell.
Downloaded the application, followed the instructions as per the Read Me.rtf file and nothing happens. I am not asked for my Admin password (I run as an admin on my Mac; but other applications actually ask for it, so that isn't the issue) and all that happens is a modal window comes up with a checkbox and message "Change NC background"; there is no way out of the window except to go to the NCBackgrounder menu and Quit. I have looked into the package and the two Automator actions therein don't work and when attempting to run, spawn error messages.
So overall, this doesn't seem to work and I would suggest people be wary of downloading it.