In CalendarView, selected dates are highlighted with a different backcolor and forecolor.

To add selected dates in CalendarView, set the SelectedDates property of C1CalendarView.

The following image shows a selected date in CalendarView.

The following code snippet shows how to add a selected date using the SelectedDates property in CalendarView.

' add a selected date 
C1CalendarView1.SelectedDates =
    New DateTime() {New DateTime(2017, 2, 23, 0, 0, 0, 0)}

// add a selected date 
c1CalendarView1.SelectedDates = new DateTime[] 
{
    new DateTime(2017, 2, 23, 0, 0, 0, 0)
};