The always visible entry bar at the bottom of the screen will help you add new tasks in no time: tap “Add Your Task...”. Type the task title and click Done. That’s it! The new task will be created in the list you’re already on, or in your default list if you’re in Today.
If you want to include other fields such as due date, favorite, tag, etc., just click the "+" button and a new window will appear where you can fill in all the task info.