How to Lock a Database table through c# code?

   private void Transaction()
        {
            string ConString = "Data Source=Server1;Initial Catalog=pubs;User ID=sa;Password=sa;";
            SqlConnection con = new SqlConnection(ConString);
            con.Open();//need to open connection first
            SqlCommand cmd = con.CreateCommand();//command from Connection
            SqlTransaction tr = con.BeginTransaction(IsolationLevel.Serializable, "MyTrans");

            cmd.CommandText = "insert into AgeTable ([Name],age) values ('tom',99)";
            cmd.Connection = con;
            cmd.Transaction = tr;
            cmd.ExecuteNonQuery();
            tr.Commit();
            con.Close();
        }

        SqlConnection connection = new SqlConnection(connectionString)
        connection.Open();

        SqlCommand command = connection.CreateCommand();
        SqlTransaction transaction;

        // Start a local transaction.
        transaction = connection.BeginTransaction("SampleTransaction");

        // Must assign both transaction object and connection
        // to Command object for a pending local transaction
        command.Connection = connection;
        command.Transaction = transaction;

        command.CommandText =
                "Insert into Region (RegionID, RegionDescription) VALUES (100, 'Description')";
        command.ExecuteNonQuery();
        command.CommandText =
                "Insert into Region (RegionID, RegionDescription) VALUES (101, 'Description')";
        command.ExecuteNonQuery();

        // Attempt to commit the transaction.
        transaction.Commit();
        Console.WriteLine("Both records are written to database.");