mcsdk-automation-csharp

```csharp
using System;
using System.Net.Http;
using System.Threading.Tasks;

namespace SalesforceMarketingCloudSDK
{
    public class MarketingCloudClient
    {
        private readonly HttpClient _httpClient;
        private readonly string _apiKey;

        public MarketingCloudClient(string apiKey)
        {
            _httpClient = new HttpClient();
            _apiKey = apiKey;
        }

        public async Task SendEmailAsync(string emailAddress, string templateId, string subject)
        {
            var request = new HttpRequestMessage(HttpMethod.Post, "https://api.marketingcloud.com/v1/email/send");
            request.Headers.Add("Authorization", _apiKey);
            request.Content = new StringContent(
                $"{{\"emailAddress\": \"{emailAddress}\", \"templateId\": \"{templateId}\", \"subject\": \"{subject}\"}}",
                System.Text.Encoding.UTF8,
                "application/json");
            
            var response = await _httpClient.SendAsync(request);
            response.EnsureSuccessStatusCode();
        }
    }
}
```

### Example Usage
```csharp
var client = new MarketingCloudClient("your-api-key");

// Send an email
await client.SendEmailAsync("user@example.com", "template123", "Welcome to Our Service");
```