Code:
public static void UploadFileRequest(string FolderID, string accesstoken)
        {

            string boundary = string.Format("----------------------------{0}", DateTime.Now.Ticks.ToString("x"));
            string filenamee = "C:\\Users\\Administrator\\Desktop\\Text.txt";
            HttpWebRequest httpWReq = (HttpWebRequest)WebRequest.Create("https://upload.box.com/api/2.0/files/content");
...