HOLA MUNDO EN FORMAS C#

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

namespace HOLA_MUNDO_FORMS

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        //CODIGO EN EL BOTON

        private void button1_Click(object sender, EventArgs e)

        {

            textBox1.Text = "HOLA MUNDO";

        }

    }

}

IMAGEN DE LA FORMA