Like in Windows operating systems (Windows 7, Vista, etc.), Ubuntu also allows its users to automatically change desktop wallpaper using your own photos. This can be done with the help of CreBS, which is a program that allows to create a desktop background slide show.
1. Install first CreBS on Ubuntu 11.04/10.10/10.04 via the Terminal with these commands:
sudo add-apt-repository ppa:crebs/ppa
sudo apt-get update
sudo apt-get install crebs
2. Using the dash, search for "crebs" and launch it.
3. Add now images to the slideshow using the Add button.
4. You can re-order images using the drag and drop feature.
5. Under the Image Defaults tab, set image time duration.
6. Insert now a name for your selection and click Apply.
7. Your background image will now change automatically. That's it!