By default with Gnome 3, desktop icons and the ability to right click on the desktop is disabled. I will show you how to enable it.
Open dconf by pressing alt + f2 and running:>
Go to org > gnome > desktop > background and check the box to show desktop icons.
While this brings back desktop icons, and enables right clicking on the desktop, it makes the computer, home, trash icons visible. These are usually hidden with Ubuntu. To make them hidden again, but still allowing icons on the desktop, go to nautilus > desktop, and uncheck the boxes for the icons you want hidden.