save file dialog c#

private void button1_Click(object sender, System.EventArgs e)
 {
     Stream myStream ;
     SaveFileDialog saveFileDialog1 = new SaveFileDialog();
 
     saveFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"  ;
     saveFileDialog1.FilterIndex = 2 ;
     saveFileDialog1.RestoreDirectory = true ;
 
     if(saveFileDialog1.ShowDialog() == DialogResult.OK)
     {
         if((myStream = saveFileDialog1.OpenFile()) != null)
         {
             // Code to write the stream goes here.
             myStream.Close();
         }
     }
 }