You can add a new To-Do item to your schedule a couple of ways.
To-do Tab
Click on the To-do Tab and then click “Create To-Do“
Select “Single To-do” or “Recurring Series of To-do“
When you choose a “Single To-do” you will first choose a date for the to-do and you can also set a time and the estimated duration of the to do. 
Next name or describe the To-do and select a category (learn how to edit and add those here)
This section is optional, but you can select customers, properties, and employees that are involved with this To-Do.
You can also change the color for this to-do that will appear on your schedule.
You can also create a To-do from the icon on the top right of your screen.
Once complete, click the blue “Create To-do” to save it.
Another way to create a new To-do is from the Schedule Tab.