gistfile1.cs

public static string PostWithAuth(string url, string requestBody = null, string method = "POST") {
  		using (WebClient client = new WebClient()) {
				var credentials = "Basic " + Convert.ToBase64String(Encoding.UTF8.GetBytes(APIKey + ":"));
				client.Headers.Add(HttpRequestHeader.Authorization, credentials);
				client.Headers.Add(HttpRequestHeader.Accept, "application/json");
				client.Headers.Add(HttpRequestHeader.ContentType, "application/json");
				client.Headers.Add(HttpRequestHeader.UserAgent, "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
				if (!String.IsNullOrEmpty(requestBody))
					return client.UploadString(url, method, requestBody);
				else
					return client.UploadString(url, method, "{}");
			}
		}