how i can insert more than one rows into more than one tables?? ( in one mehtod ) when user click 'Send Message Button'

 private void button1_Click(object sender, EventArgs e)
        {
            List<string> UsersList = new List<string>(); 

            SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True");
            con.Open();
            SqlCommand comm = new SqlCommand("select Username from Users", con);
            SqlDataReader reader = comm.ExecuteReader();
           
            //Clear the UserList before Filling new
            UsersList.Clear(); 
           
            //Loop through all The users and Add Them to list For Sending 
            while (reader.Read())
            {
                UsersList.Add(reader["Username"].ToString());
            }

            // Now Execute insert Query on All Usernames in List 
            foreach (string user in UsersList)
            {
                comm = new SqlCommand("Insert into Users(Username,Message) values('" + user + "','testmsg')", con);
                comm.ExecuteNonQuery();
                
            }

            //Finaly Close the Connection 
            con.Close(); 
       
         }