Alerts are available both for Tasks and Events. In order to be alerted a date and time have to have been set. By default, new Tasks and Events are set to alert you at the time set, but you can override this by tapping on the ‘Set date’ icon in the expanded Task or Event window, and then on the Bell icon at the bottom. Use the time scroller to choose how many minutes or hours before the set Task or Event time you wish to be alerted. You can also tap one of the preset times below the scroller (which can be customised by going to Settings -> Early Alert).