Progress bar with Background worker till xml file gets uploaded.

Question

Hi,
how i can run a progress bar on winform to tell the user to wait till the xml file is being uploaded in treeview on winform?
i am getting an exception on  xmlDocument.Load(txtFileName.Text);
Thanks

       private void btnBrowse_Click(object sender, EventArgs e)
        {          
            OpenFileDialog open = new OpenFileDialog();
            if (open.ShowDialog(this) == DialogResult.OK)
            {
                txtFileName.Text = open.FileName;
                treeDocLoadMethod(open.FileName); //this variable gives the name of selected file
                bgWorker.RunWorkerAsync();
            }
        }//Browse button
       private void bgWorker_DoWork(object sender, DoWorkEventArgs e) 
        {  
            xmlDocument = new XmlDocument();  
            Thread.Sleep(500);  
            xmlDocument.Load(txtFileName.Text);  
            btnBrowse.Enabled = false;  
        }  
        private void bgworker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
         {
             // Set progress bar to 100% in case it's not already there.
             StripProgressBar.Value = 100;
             if (e.Error == null)
             {
                 MessageBox.Show(xmlDocument.InnerXml, "Download Complete");
             }
             else
             {
                 MessageBox.Show("Failed to download file");
             }
             // Enable the Browse button and reset the progress bar.
             this.btnBrowse.Enabled = true;
             StripProgressBar.Value = 0;
             toolStripStatusLabel1.Text = "work finished processing request.";  
     }//workerCompleted