Add the extension using the Extension Manager.

The FE users can indicate to which events they want to be notified. Just add the “User Notification Preferences” plugin to a page where you want. The only configuration you can currently do of the FE plugin is change the text by modifying the correct entries in the pi1/locallang.xml file.

The BE users can indicate their preferences in the User > BE Notifications section.

As a BE administrator, you can decide which predefined notifications should be switched on and which not, you can check which FE and BE users want to be notified of what events, you can check the history of sent notifications, and you can create custom notifications. All these options are available under the Tools > Notifications menu.