在C#中，使用Exchange Web Services (EWS) 創建日歷事件需要以下步驟：

1. 安裝EWS Managed API。可以通過NuGet包管理器或從Microsoft官方網站下載并安裝。

2. 添加引用。在項目中添加對Microsoft.Exchange.WebServices.dll的引用。

3. 編寫代碼。以下是一個簡單的示例，展示了如何使用EWS Managed API創建日歷事件：

using System;
using Microsoft.Exchange.WebServices.Data;

namespace EwsCreateCalendarEvent
{
    class Program
    {
        static void Main(string[] args)
        {
            // Exchange服務器的URL
            string exchangeUrl = "https://your-exchange-server/ews/exchange.asmx";
            // 用戶的電子郵件地址和密碼
            string userEmail = "user@example.com";
            string userPassword = "your_password";

            // 創建ExchangeService對象
            ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2010_SP2);
            service.Credentials = new WebCredentials(userEmail, userPassword);
            service.Url = new Uri(exchangeUrl);

            // 創建日歷事件
            Appointment appointment = new Appointment(service);
            appointment.Subject = "My Calendar Event";
            appointment.Body = "This is a test event.";
            appointment.Start = DateTime.Now.AddHours(1);
            appointment.End = DateTime.Now.AddHours(2);
            appointment.Location = "Conference Room A";
            appointment.ReminderMinutesBeforeStart = 15;

            // 保存日歷事件
            appointment.Save(SendInvitationsMode.SendToNone);

            Console.WriteLine("Calendar event created successfully.");
        }
    }
}

請確保將exchangeUrl、userEmail和userPassword替換為實際的Exchange服務器URL和用戶憑據。此示例將在當前時間的1小時后創建一個名為"My Calendar Event"的日歷事件，持續1小時，位于"Conference Room A"。

注意：這個示例僅適用于Exchange 2010 SP2及更高版本。如果你使用的是較舊版本的Exchange，請根據需要調整ExchangeVersion枚舉值。