Enabling an application is easy. Just go to the Content Management tab in the site admin pages, then the Applications subtab. Click Enable next to the Application you wish to use. You can then choose a URL for the application and click OK.
The application will now appear in the Site Map.
You can click on the application in the site map to administer it. Though for most of them - such as the Photo Albums and Events Calendar, new items are added though the pages on the live website.
To find out more about each application, see the Applications section of the main Voice documentation.