Использование пользовательского приложения Facebook и SDK Facebook
var facebookClient = new FacebookClient(FbConf.testimonialsAppId, FbConf.testimonialsAppSecret);
IDictionary<string, string> parameters = new Dictionary<string, string>();
parameters.Add("message","message on the wall"));
parameters.Add("created_time", DateTime.Now.ToString());
dynamic result = facebookClient.Post(string.Format("{0}/feed", FbConf.testimonialsAppId), parameters);
var id = result.id;