the calling thread must be sta because many ui components require

I want to show the animated progressbar while saving view
the above code is the one I'm experimenting on but it gives me an error saying:

" The calling thread must be STA, because many UI components require this."
The error appears on the constructor of the Page i'm loading.

I have no idea now what to do. Is there any way I can make this simpler as this is my frist time to use BackgroundWorker..

private void OnScreenShotAllCommandExecuted(object parameter)
        {
            UserControl view = new UserControl();
             view.Show();  
            SaveAllScreen saveScerrn = new SaveAllScreen();
            worker.RunWorkerAsync(saveScerrn);

        }
        private void worker_DoWork(object sender, DoWorkEventArgs e)
        {
            SaveAllScreen.OnScreenShotAllCommand();

                if (worker.CancellationPending)
                {
                    e.Cancel = true;
                    return;
                }
        }
        private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                MessageBox.Show("Search cancelled.");
            }
            else if (e.Error != null)
            {
                // An error was thrown by the DoWork event handler.
                MessageBox.Show(e.Error.Message, "An Error Occurred");
            }
        }