Steps to upload file using asp.net send through mobile app

This is how I achieved File Upload using WebMethod , both android & Apple applications used this WebMethod for uploading files on server, I tested it using google chrome extension Advanced rest client for reading more about rest API Client Click Here

[WebMethod]
public void UploadFile()
{
    FileResponse master = new FileResponse();
    //HTTP Context to get access to the submitted data
    HttpContext postedContext = HttpContext.Current;
    //File Collection that was submitted with posted data
    HttpFileCollection Files = postedContext.Request.Files;
    string sessionId = Server.UrlDecode((string)postedContext.Request.Form["sessionId"]);
    master.sessionId = sessionId;
    master.timeStamp = DateTime.Now.DdMonYyyy_HhMmSs();
    master.status = Status.Failure;
    master.sessionStatus = Status.Failure;
    master.message = "Image not found";
    try
    {
        if (isGuest_Employee(sessionId))
        {
            //Make sure a file was posted
            string fileName = string.Format("feedbackImgSign_{0}.png", Helper.LDFileNumberSeq);
            if (Files.Count == 1 && Files[0].ContentLength >= 1)
            {
                //The byte array we'll use to write the file with
                byte[] binaryWriteArray = new
                byte[Files[0].InputStream.Length];
                //Read in the file from the InputStream
                Files[0].InputStream.Read(binaryWriteArray, 0,
                (int)Files[0].InputStream.Length);
                //Open the file stream
                FileStream objfilestream = new FileStream(Helper.UploadedFilesDirectory + "\\" +
                fileName, FileMode.Create, FileAccess.ReadWrite);
                //Write the file and close it
                objfilestream.Write(binaryWriteArray, 0,
                binaryWriteArray.Length);
                objfilestream.Close();

                master.FILE_NAME = fileName;
                master.status = Status.Success;
                master.sessionStatus = Status.Success;
                master.message = "Image uploaded successfully!";
            }
        }
        else
        {
            master.status = Status.Failure;
            master.sessionStatus = Status.Failure;
            master.message = "Unable to authenticate provided session Id";
        }
    }
    catch (Exception ex)
    {
        master.status = Status.Failure;
        master.message = ex.Message;
    }

   string strJSON = JsonConvert.SerializeObject(master, Formatting.Indented,
           new JsonSerializerSettings { ReferenceLoopHandling = ReferenceLoopHandling.Ignore });

    Context.Response.Clear();
    Context.Response.ContentType = "application/json";
    Context.Response.Write(strJSON);
}