C#: looping threads

hello

I use this link:

http://www.geekpedia.com/tutorial179_Creating-a-download-manager-in-Csharp.html

I want my program to read "address file" and download URLs line by line.

I edit code thus, but my program can not read next line of "address file".

private void Download()
        {
            using (WebClient wcDownload = new WebClient())
            {
                try
                {
                    String FilePath_address = Application.StartupPath + @"\address.txt";
                    string line = "";
                    // Read the file and display it line by line.
                    System.IO.StreamReader file = new System.IO.StreamReader(FilePath_address);
                    while ((line = file.ReadLine()) != null)
                    {
                        if (txtUrl.InvokeRequired)
                        {
                            MessageBox.Show("1");
                            txtUrl.Invoke(new Action(() => txtUrl.Text = line));
                        }
                        else
                        {
                            txtUrl.Text = line;
                        }
                        if (txtPath.InvokeRequired)
                        {
                            MessageBox.Show("2");
                            txtPath.Invoke(new Action(() => txtPath.Text = Application.StartupPath + @"\D1.pdf"));
                        }
                        else
                        {
                            txtPath.Text = Application.StartupPath + @"\D1.pdf";
                        }
                        // Create a request to the file we are downloading
                        webRequest = (HttpWebRequest)WebRequest.Create(txtUrl.Text);
                        // Set default authentication for retrieving the file
                        webRequest.Credentials = CredentialCache.DefaultCredentials;
                        // Retrieve the response from the server
                        webResponse = (HttpWebResponse)webRequest.GetResponse();
                        // Ask the server for the file size and store it
                        Int64 fileSize = webResponse.ContentLength;
                        // Open the URL for download 
                        strResponse = wcDownload.OpenRead(txtUrl.Text);
                        // Create a new file stream where we will be saving the data (local drive)
                        strLocal = new FileStream(txtPath.Text, FileMode.Create, FileAccess.Write, FileShare.None);
                        // It will store the current number of bytes we retrieved from the server
                        int bytesSize = 0;
                        // A buffer for storing and writing the data retrieved from the server
                        byte[] downBuffer = new byte[2048];
                        // Loop through the buffer until the buffer is empty
                        while ((bytesSize = strResponse.Read(downBuffer, 0, downBuffer.Length)) > 0)
                        {
                            // Write the data from the buffer to the local hard drive
                            strLocal.Write(downBuffer, 0, bytesSize);
                            // Invoke the method that updates the form's label and progress bar
                            this.Invoke(new UpdateProgessCallback(this.UpdateProgress), new object[] { strLocal.Length, fileSize });
                        }
                        if (prgDownload.InvokeRequired)
                        {
                            prgDownload.Invoke(new Action(() => prgDownload.Value = 0));
                        }
                        else
                        {
                            prgDownload.Value = 0;
                        }
                        if (lblProgress.InvokeRequired)
                        {
                            lblProgress.Invoke(new Action(() => lblProgress.Text = "Next Download Starting"));
                        }
                        else
                        {
                            lblProgress.Text = "Next Download Starting";
                        }
                        // Close the web response and the streams
                        //webResponse.Close();
                        //strResponse.Close();
                        //strLocal.Close();
                        // Abort the thread that's downloading
                        //thrDownload.Abort();
                        // Create a new thread that calls the Download() method
                        thrDownload = new Thread(Download);
                        // Start the thread, and thus call Download()
                        thrDownload.Start();
                    }
                }
                finally
                {
                    // When the above code has ended, close the streams
                    strResponse.Close();
                    strLocal.Close();
                    
                }
            }
        }