To set the reminder choose the Reminder tab in the Create Task dialog or in the Edit Task dialog.
Check Reminder box and the reminder parameters will become active.
Note: Parameter " Before" will be active only if you set the Due date on the General tab.
You can define the time you need the reminder to start at and choose how many minutes, hours, days or weeks you need before the defined date .
Also you can choose the sound file to be played with the reminder and e-mail, you want reminder to be sent to.