This will work if your computer started with 3D Accelerated drivers, and if not, when you select the "Extra" effects, you will be asked if you want to activate the drivers. This is done very simple, you don't need to know anything about Linux, don't worry.
If you want advanced desktop effects, I will recommend you to install two applications. I'm using them on my computers with Linux, and I am recommending them to you because I know that they are simple to be configured and won't create conflicts.
Go to Synaptic Package Manager (System -> Preferences) and there search for the following two applications, and mark them both for installation (the search will return two applications, mark them both):
Please note that this will work on 3D Accelerated drivers, which are either automatically activated, or are manually activated by you). If you can't find the driver for your graphic card, try to search on manufacturer's website (you will need advanced knowledge for configuration).
Enjoy you 3D Ubuntu desktop effects !