Click the main menu icon (located in the top right of the screen) to bring up the calendar side bar right below it.
Scroll down to Reminders. Click options for Reminders. Then select "Switch to Tasks".
Another side bar will now appear on the right side of the screen. Within that side bar, you can add a task by clicking the + sign located at the bottom of the side bar.
Click the arrow that appears to the right of your new to be able to add notes and a due date for the task.
Once you are finished, the task will now appear as part of your calendar if you added a due date. If you did not add a due date, it can always be found in the tasks side bar.