I don't have Calendar Control 12, but I do have Calendar Control 11.
Unless MS have made a major change to version 12, I don't think that you can add tasks to it - it is just a calendar that can be used to pick dates.
Right-click the Calendar Control and look at it's Properties. In version 11 there are no accessible properties for individual days. If version 12 is the same then you will need a different approach - there are a number of shareware, and paid personal manager type programs around.