I found the answer;
public CalendarEntry CreateCalendar(string title, string summary, string timezone, bool ispublic)
{
CalendarEntry calendar = new CalendarEntry();
calendar.Title.Text = title;
calendar.Summary.Text = summary;
calendar.TimeZone = timezone;
Uri postUri = new Uri("https://www.google.com/calendar/feeds/default/owncalendars/full");
CalendarEntry createdCalendar = (CalendarEntry) _calendarService.Insert(postUri, calendar);
return createdCalendar;
}