This document explains how to create a task/reminder in Apple iCal (Mac OS 10.5-7) or Calendar (Mac OS 10.8-10).
In iCal/Calendar a task is called a Reminder and they are associated with configured calendars. When reminders are displayed, the main iCal/Calendar window shows them in a column headed by Reminders to the right side of the events. To show/hide the Reminders display, from the menubar select View -> Show/Hide Reminders. You can select as well how reminders are sorted and whether to show Completed reminders from the same View menu. Selecting a reminder, then clicking the right button on a two-button mouse (or CTRL-click with a single button mouse) will provide yet more options for a reminder.
iCal/Calendar also provides something called a Reminder List which you can use to organize different areas of your life (work, home, school, and so on) or for every task you are working on. (Reminder Lists are available in Mac OS X version 10.7.2 or later.) Note especially that when you configure an iCal/Calendar CalDAV account for Office 365, a set of Reminder Lists are created for each calendar discovered during the account set up process.
Any Reminder Lists you create appear in the Reminders pop-up menu. In the Reminders pop-up menu, you can select to show or hide individual Reminder Lists. You activate the pop-up menu by showing Reminders. Note the small downward-facing triangle to the right of the Reminders heading--click on it to view the Reminder Lists you have created and to select which are viewed or hidden.
There are several ways you can create a reminder:
On Mac OS 10.9 and 10.10 there is an application called Reminders meant to create and manage both lists and reminders. To create a reminder: