How can I do withdraw variable value and paste in template string

Hi!  All my friends!
Please help me, it’s my first project  for airport (student practice).  I’m learning coding C# My Data base connected  to  forms DataGridView and I see any changes real time (used SqlDependency).

Next step, how can I do for example when changes one column in Database (flight condition)  withdraw "flight_number, destination_airport" and paste this information (variable value) in template string "Dear passenger ''flight_number'' to ''destination_airport'' was canceled. (passenger display notifications). 
How can I do for C#, please give an example code. sorry my English, i hope you understand me. Thank you!

//Load Data
       void LoadData()
       {
           DataTable dt = new DataTable();
           if (con.State == ConnectionState.Closed)
           {
               con.Open();
           }
           SqlCommand cmd = new SqlCommand("SELECT flight_number, destination_airport, flight_status, checkin_place, gate FROM DFP", con);
           cmd.Notification = null;

           SqlDependency de = new SqlDependency(cmd);
           de.OnChange += new OnChangeEventHandler(de_OnChange);

           dt.Load(cmd.ExecuteReader(CommandBehavior.CloseConnection));
           dataGridView1.DataSource = dt;

       }
       public void de_OnChange(object sender, SqlNotificationEventArgs e)
       {
           SqlDependency de = sender as SqlDependency;
           de.OnChange -= de_OnChange;
           if (OnNewHome != null)
           {
               OnNewHome();
           }
       }
   }