To Do List overlays allow you to create a combined view of your Calendars and To Do Lists by layering your To Do List on top of your calendar. You can overlay a To Do List on your calendar whether or not you've assigned start or due dates to your Tasks. Below is what your Tasks will look like overlaid onto your calendar if you've assigned a start date, a start and end date, an end date, and no date.

You can easily change the date of Tasks in your calendar in two ways: by using drag-n-drop in the calendar, or by clicking on the task in your calendar and editing it. 

Using drag-n-drop to change the Task date or time

If you use drag-n-drop and your task only has a start date or due date assigned, then only the start date or due date will be changed. If you have a start date and a due date assigned, then both of the times will be affected. See the image below on dragging your event to a new date:

If you are using "Day View" or "Week (column) View" in your calendar will be divided into time slots known as the Day Grid. If your Tasks don't have a due or start date assigned, they will show either at the top or bottom of each day. You can drag these tasks to a time slot in your calendar and your Task will automatically be given a time. See the image below:

Using the To Do List pop-up to edit Tasks

When you click on any Task in your To Do List overlay on your calendar a pop-up will appear with a copy of your To Do List in it. You can click on the tasks in this dialog to make any changes that you'd like, all without having to leave your calendar. Any changes you make to your To Do List pop-up will be instantly reflected in your To Do application. See the image below: