class User{
    //var
        private string  name;
        private string password;
  // constructors
        public User(){
            name = String.Empty;
            password = String.Empty;
            number = 0;
        }
    public User(string name, string password)
        {
            this.name = name;
            this.password = password;
        }
  //rest
  }

 Class 1{
    private 2 obiekt_klasy_2;


    ///
    private void button_create_Click(object sender, EventArgs e)
        {
           obiekt_klasy_2.CreateUser(textBox_username.Text, textBox_password.Text);
        }

    private void button_users_Click(object sender, EventArgs e)
        {
            foreach(User us in users){
                listBox1.Items.Add("Name: " + us.GetName() + " Password: " + us.GetPassword() + " Number: " + us.GetNumber());
            }
        }
    ///
 }

 Class 2{

    private static List<User> users;
    public void CreateUser(string name, string password)
        {
          users.Add(new User(name, password));
            label_Login.Text = "";
        }

}