I used this command:

It deleted all the files, so I restarted the phone and there were only 4 desktops left OK that is fine - I added the rest 5 of them but the same problem appeared I cannot change the wallpaper and now I have 5 dark desktops

Also tried:
and I get that there is no such a package - gpefilemanager

Such a mess !!

Edit:
I noticed that my phone doesn't want to make *.png copies in /home/user/.backgrounds/* so a manually moved one *.png file called background-5.png and it worked I am able to see the picture but when I start Home Screen Selector they are only 4 pictures on it (from first to forth)

The question is: why is this happening how can I get it fixed to work like before ??

OK if there is no solution, I have something else in mind. I am Linux newbie and I don't know how to do that. What I mean is that in Windows they are those *.bat files that you can put many Dos commands and then to start them all at ones without typing each time, what I am trying to say is that - How can I make I script with for example this command in it = "mv background-5.png /home/user/.backgrounds" ?

It might sounds lame to you but as I all ready said I am a Linux beginner !!

Have you tried Maemodder for changing backgrounds? Quick and easy. Instructions and links on the page.

Nope It didn't help after installing It messed it up with my 9-th desktop (cleared all the widgets up and put black screen) I was able to changed only with manually putting the image in /home/user/.backgrounds

Hey guys maemodder worked fine i have 9 desktop and i changed the 9 images with it but i have to resize images .png for background 5 6 7 8 9 to 800x480 it worked fine .BUT the home screen selector shows only 4 images..