Press Atl + F2 and run:
Navigate to apps > nautilus > preferences and uncheck show_dekstop.
Next, open the Compiz Setting Manager and go to the Wallpaper plugin.
Click “New” to choose a wallpaper for your first workspace.
Browse to select an image.
Repeat the steps for all your workspaces. Once done, enable the wallpaper plugin.
Unity’s theme will look weird after enabling the plugin. Restarting the computer will fix it.