I have written about a manual way to enable Windows 7 like background auto-change functionality in Ubuntu Gnome. But it might be a little complex for someone new to Ubuntu, and therefore this tutorial brings an easy use GUI tool for Gnome & Xfce desktop to change background wallpapers automatically.
DesktopNova is this GUI supports png, jpg, jpeg, bmp, svg, gif and tif image formats. With DesktopNova you can choose the images from single files and/or from folders (include subfolders if you wish), determine whether the program should start when you log in or not.
DesktopNova is available in Ubuntu official repository, just search and install in
Ubuntu Software Center or use this command instead:
sudo apt-get install desktopnova
Now, launch DesktopNova from Applications -> Accessories menu, and choose images or folder in first tab.
Head to Settings tab and choose change wallpaper in minutes or change in every login, select autorun, and most important remember to click Modules and choose one.
Finally, click Start Daemon to start the program.