在C#中，要使用ClientWebSocket類連接到WebSocket服務器，您需要首先安裝System.Net.WebSockets NuGet包。然后，您可以按照以下步驟創建一個簡單的WebSocket客戶端：

1. 導入必要的命名空間：

using System;
using System.Net.WebSockets;
using System.Threading.Tasks;

2. 創建一個WebSocket客戶端類：

public class WebSocketClient
{
    private readonly string _url;

    public WebSocketClient(string url)
    {
        _url = url;
    }

    public async Task ConnectAsync()
    {
        using (var client = new ClientWebSocket())
        {
            try
            {
                await client.ConnectAsync(_url, CancellationToken.None);
                Console.WriteLine("Connected to WebSocket server.");

                // 在這里發送和接收數據
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error: {ex.Message}");
            }
            finally
            {
                await client.CloseAsync(WebSocketCloseStatus.NormalClosure, "Closed by client", CancellationToken.None);
            }
        }
    }

    public async Task SendMessageAsync(string message)
    {
        if (client != null && client.State == WebSocketState.Open)
        {
            var buffer = System.Text.Encoding.UTF8.GetBytes(message);
            await client.SendAsync(new ArraySegment<byte>(buffer), WebSocketMessageType.Text, true, CancellationToken.None);
            Console.WriteLine($"Sent message: {message}");
        }
    }

    public async Task<string> ReceiveMessageAsync()
    {
        if (client != null && client.State == WebSocketState.Open)
        {
            var result = new StringBuilder();
            var buffer = new byte[1024 * 4];
            WebSocketReceiveResult receiveResult;

            do
            {
                receiveResult = await client.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
                result.Append(System.Text.Encoding.UTF8.GetString(buffer, 0, receiveResult.Count));
            }
            while (!receiveResult.CloseStatus.HasValue);

            return result.ToString();
        }

        return null;
    }
}

3. 在主程序中使用WebSocket客戶端連接到服務器：

class Program
{
    static async Task Main(string[] args)
    {
        var url = "ws://your-websocket-server-url";
        var webSocketClient = new WebSocketClient(url);

        await webSocketClient.ConnectAsync();

        // 發送消息
        await webSocketClient.SendMessageAsync("Hello, WebSocket server!");

        // 接收消息
        var message = await webSocketClient.ReceiveMessageAsync();
        Console.WriteLine($"Received message: {message}");
    }
}

請注意，您需要將your-websocket-server-url替換為您的WebSocket服務器URL。運行此程序后，它將連接到WebSocket服務器，發送一條消息，然后接收并打印服務器返回的消息。