iCalendar calendar = new iCalendar();
calendar.Method = "PUBLISH";

Event evt = calendar.Create<Event>();

var attendes = new List<IAttendee>();
//required attendee
IAttendee attendee1 = new DDay.iCal.Attendee("MAILTO:myid@gmail.com")
{
    CommonName = "Naveen Jose",Role = "REQ-PARTICIPANT"
};
attendes.Add(attendee1);
//optional attendee
IAttendee attendee2 = new DDay.iCal.Attendee("MAILTO:someid@codovations.com")
{
    CommonName = "Noah Naveen",Role = "OPT-PARTICIPANT"
};
attendes.Add(attendee2);
if (attendes != null && attendes.Count > 0)
{
    evt.Attendees = attendes;
}