How do I use desktop effects in Ubuntu 11.04
2 Answers
You'll need to provide more information about your computer in order for a fuller answer, but I'll do my best to help.
If you are seeing the new Unity interface then your computer is capable of 3D compositing effects but they are not toggled via the menu previously available in the Appearance menu.
If you want to change which effects are in use, you should install the CCSM by typing sudo apt-get install compizconfig-settings-manager
into a terminal window. This will install a utility that lets you enable, disable or change any Compiz effects.
If you are not seeing the Unity interface and are being forced into the Classic Desktop (with the old GNOME Panels) then your computer may not be capable of running Compiz or you may have to install proprietary graphics drivers.