Where are the Desktop wallpapers located in Lubuntu
On Lubuntu the wallpapers are located in the /usr/share/lubuntu/wallpapers directory.
To transfer your favourite wallpaper to this directory you will need root access.
As an example my favourite wallpaper is located as a .jpeg on my Desktop. In order to transfer this to the wallpapers directory we would issue the following command.
sudo cp /home/your_username/Desktop/your_image_name.jpeg /usr/share/lubuntu/wallpapers
Once transferred, select Preferences >> LXQT settings >> Desktop from the Lubuntu menu, then select the wallpaper you just transferred.
If you prefer you can transfer your wallpaper without using the terminal. Please visit the tutorial below that shows you have to access your folders and files as a root user.
Where the desktop wallpapers location in Xubuntu