Add users and permission to directory and files by using c#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using Microsoft.Win32.SafeHandles;
using System.IO;
using System.Security.AccessControl;
using System.Security.Principal;

namespace WinTest
{
    public partial class PermissionTest : Form
    {
        public PermissionTest()
        {
            InitializeComponent();
        }

        private void PermissionTest_Load(object sender, EventArgs e)
        {
            string dirName1 = @"c:\Test1";
            //string userName = System.Environment.MachineName +@"\Network Service";
            //string userName = System.Environment.MachineName +@"\ASPNET";
            string userName = "NETWORK SERVICE";
            DirectoryInfo dInfo1 = new DirectoryInfo(dirName1);
            DirectorySecurity dSecurity1 = dInfo1.GetAccessControl();
            dSecurity1.AddAccessRule(new FileSystemAccessRule(userName, FileSystemRights.FullControl, InheritanceFlags.ContainerInherit | InheritanceFlags.ObjectInherit, PropagationFlags.None, AccessControlType.Allow));
            dInfo1.SetAccessControl(dSecurity1);
        }
    }
}