Custom Error Logging in C#

1. Cratre a ErrorLogging.txt text file in C:\TestFolder folder

2. if ErrorLogging.txt Exceed 4MB then move this file to C:\TestFolder\BackUpFiles folder and    rename as ErrorLogging_<TimeStamp>.txt.
3. as usally create a new ErrorLogging.txt text file in C:\TestFolder

using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ErrorLogging

{

    class ErrorLoggingProgram

    {

        static void Main(string[] args)

        {

            string directory = @"C:\TestFolder";

            try

            {

                if (!Directory.Exists(directory))

                {

                    DirectoryInfo di = Directory.CreateDirectory(directory);

                }

            }

            catch (IOException ioex)

            {

                Console.WriteLine(ioex.Message);

            }

            string errormsg = "first line";

            if (File.Exists(@"C:\TestFolder\ErrorLogging.txt"))

                using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"C:\TestFolder\ErrorLogging.txt", true))

                {

                    file.WriteLine(errormsg);

                    file.Flush();

                    file.Close();

                    FileInfo fi = new FileInfo(@"C:\TestFolder\ErrorLogging.txt");

                    var size = fi.Length;

                    if (File.ReadAllBytes(@"C:\TestFolder\ErrorLogging.txt").Length >= 4 * 1024 * 1024) // (4MB) File to big? Create new

                    {

                        Console.WriteLine("File Size in Bytes: {0} greater than 10kb", size);

                        moveFile();

                    }

                    Console.WriteLine("File Size in Bytes: {0}", size);

                }

            else

                using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"C:\TestFolder\ErrorLogging.txt", true))

                {

                    file.WriteLine(errormsg);

                    Console.WriteLine("Does not Exist" + "\t" + @"C:\TestFolder\ErrorLogging.txt");

                    file.Flush();

                    file.Close();

                }

            Console.ReadKey();

        }

        private static void moveFile()

        {

            string directory = @"C:\TestFolder\BackUpFiles";

            try

            {

                if (!Directory.Exists(directory))

                {

                    DirectoryInfo di = Directory.CreateDirectory(directory);

                }

            }

            catch (IOException ioex)

            {

                Console.WriteLine(ioex.Message);

            }

            string sourceFile = @"C:\TestFolder\ErrorLogging.txt";

            string timeStamp = DateTime.Now.ToString("yyyyMMddHHmmssffff");

            string destinationFile = @"C:\TestFolder\backupfiles\ErrorLogging_" + timeStamp + ".txt";

            System.IO.File.Move(sourceFile, destinationFile);

        }

    }

}