If you want to know more about the extensions that come with Joomla! 1.6, take some time to explore the About Joomla! | Using Joomla! | Using Extensions menu in the sample site data. This contains links to examples of all extensions currently on board:
To find out more about the available modules and their features, it's a good idea to explore the Module Manager. In the backend, navigate to Extensions | Module Manager and click on the New button to see a pop up screen containing a full list of available modules. If you want to know what these modules do, navigate with your mouse cursor over module names. A brief explanation appears in a pop up screen. An example is shown below:
Clicking on any of the module names takes you to the Module Manager edit screen, allowing you to browse (and set) the full set of available options for this module. If you don't want to use the module you're exploring currently, click on Cancel to close the screen and return to the...