how to get process status in ASP.NET

hello every one,
if I have a function like this


private void StartExport(String filepath)
    {
        Button1.Enabled = false;
        //create a new background worker, to do the exporting
        BackgroundWorker bg = new BackgroundWorker();
        bg.DoWork += new DoWorkEventHandler(bg_DoWork);
        bg.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bg_RunWorkerCompleted);
        bg.RunWorkerAsync(filepath);
    }


private void bg_DoWork(object sender, DoWorkEventArgs e)
    {
        string query;
        query = " call sp_outtop10callcutomerby ...