This article describes how can you use tiny url for twitter

 public   string TinyUrl(string Url)
        {  try
            {
                if (Url.Length <= 30)
                {
                    return Url;
                }
                if (!Url.ToLower().StartsWith("http") && !Url.ToLower().StartsWith("ftp"))
                {
                    Url = "http://" + Url;
                }
                var request = WebRequest.Create("http://tinyurl.com/api-create.php?url=" + Url);
                var res = request.GetResponse();
                string text;
                using (var reader = new StreamReader(res.GetResponseStream()))
                {
                    text = reader.ReadToEnd();
                }

                return text;
            }

            catch (Exception)
            {

                return Url;

            }
        }

You can use this function to create tiny url