namespace Mridul
{
static class Entry
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MridulForm());
}
}
}

form codes -

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 Mridul
{
public partial class MridulForm : Form
{
public MridulForm()
{
InitializeComponent();
}
private void MridulForm_Load(object sender, EventArgs e)
{
stringTextBox.Text = @"""Hello World""";
}

}
}