Multiclient Patcher Codigo

Bueno este es un código de un MC Patcher por Klusbert, el código original estaba en VB 2010, pero por necesidad lo pase a C#, como en si el código no es mio se los dejo para que vean maso-menos como funciona.

using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;
using System.IO;

namespace MC
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            byte OriginalByte = 117;
            byte Patched = 235;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            long SearchFor;
            SearchFor = 0x001079B4;
            OpenFileDialog Dlg = new OpenFileDialog();
 Dlg.Filter = "Executable files (*.exe)|*.exe|All files (*.*)|*.*";

 if (Dlg.ShowDialog() == DialogResult.OK) {
  string Filename = Dlg.FileName;
  string Directory = System.IO.Path.GetDirectoryName(Filename);

  FileVersionInfo Fvi = FileVersionInfo.GetVersionInfo(Filename);
  string Pversion = Fvi.FileVersion;
  if (Pversion != "8.70") {
   MessageBox.Show("This version is not suported.");
   System.Environment.Exit(0);
  }

  FileStream fsr = new FileStream(Dlg.FileName, FileMode.OpenOrCreate, FileAccess.ReadWrite);
  fsr.Seek(SearchFor, SeekOrigin.Begin);
  int pos = Convert.ToInt32(fsr.Position);

  int RedByte = fsr.ReadByte();
  if (RedByte == 117) {
   File.Copy(Filename, Directory + "\\" + "Tibia.exe.bak", true);
   MessageBox.Show("Done!");
   fsr.Position = pos;
   fsr.WriteByte(235);
  } else if (RedByte == 235) {
   MessageBox.Show("Already Patched");
  } else {
   MessageBox.Show("Error something went wrong..");
  }
  fsr.Close();
 }
        }
    }
}