how to save(upload) wav file in silverlight

i want to save(Upload) file in silverlight in silverlight application folder
i get url of the application
 string str3 = App.Current.Host.Source.AbsoluteUri + "/Recording/";
but i can't know how to save file
i use this code.....plz help

 
            string extension = "wav";



            // Create an instance of the open file dialog box.
            OpenFileDialog openFileDialog1 = new OpenFileDialog();

            // Set filter options and filter index.
            openFileDialog1.Filter = String.Format("{1} files (*.{0})|*.{0}|WAV FILES (*.*)|*.*", extension, "Audio");
     & ...