Please teach me how to handle the text file ( clock in-out )

using System;
using System.IO;

namespace _125812
{
class Program
{
static void Main(string[] args)
{
String Buffer;
String id;
int year, month, day, hour, minute;
DateTime dt = new DateTime();
char io;
// you must change the filename in the StreamReader
using (StreamReader sr = new StreamReader(@"Data.txt"))
{
while (!sr.EndOfStream)
{
Buffer = sr.ReadLine();
id = Buffer.Substring(0, 10);
day = ConvertNumber(Buffer.Substring(10, 2));
month = ConvertNumber(Buffer.Substring(12, 2));
year = ConvertNumber(Buffer.Substring(14, 4));
hour = ConvertNumber(Buffer.Substring(18, 2));
minute = ConvertNumber(Buffer.Substring(20, 2));
io = Buffer[22];
dt = new DateTime(year, month, day, hour, minute, 0);
Console.WriteLine("{0} {1} {2}", id, dt, io);
}
}
}

static int ConvertNumber(String text)
{
int i;
// Int32.TryParse returns true if the text was converted to a number
if (Int32.TryParse(text, out i))
return i;
Console.WriteLine("Invalid data: {0}", text);
return 0;
}
}
}