On the left, there is a vertical menu To do list, select it. You'll see  a small window with a field where you can enter tasks. After you filled the information in the box, select To calendar, located at  the bottom,  right to Done, Edit, Delete.
            Once you show small window New event, you can fill in the fields (date, time) of advanced settings you can add a location, category, description. When you're done, click Create event.