How do i save file with filename, Date and time. using windows form SaveFileDialog

Hi

I want to create or save files with filename ,date, time....can some one help me with this?

Stream myStream;
            SaveFileDialog saveFileDialog1 = new SaveFileDialog();
 
            //saveFileDialog1.Filter = "txt files (*.xml)|*.xml(*.txt)|*.txt|All files (*.*)|*.*";
            saveFileDialog1.Filter = "File Type (*.xml)|*.xml";
            saveFileDialog1.FilterIndex = 2;
            saveFileDialog1.RestoreDirectory = true;
            saveFileDialog1.FileName = txtBackupFile.Text;
           
            DateTime currentDateTime = DateTime.Now;
            String dateStr = currentDateTime.ToString("yyyy-MM-dd HH_mm_ss");
 
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                if ((myStream = saveFileDialog1.OpenFile()) != null)
                {
                    // Code to write the stream goes here.
                    //this.lblBackupPath.Text = "c:\tmp";
                    txtBackupFilePath.Text = saveFileDialog1.FileName.Substring(dateStr);
                    myStream.Close();
                }
            }

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