Código de C sharp - Hola mundo c# con windows form

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace hola_mundo

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e) //CODIGO DEL BOTON

        {

            MessageBox.Show("Hola Mundo");

            Close();

        }

    }

}