private void btn_Browse_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.RestoreDirectory = true;

            if (ofd.ShowDialog() == DialogResult.OK)
            {
                txt_upload.Text = ofd.FileName;

                byte[] file = File.ReadAllBytes(txt_upload.Text);
            }
        }