Creating Notepad application

I want 2 create notepad application, but I need to read text file using System.IO.File class which have open method which returns some sort of FileStream object and it accepts bytes array, buffer length and bytescount. So can anybody give gorgeous example how can i use that in this application and also other areas where it can be used(as i expect this same can be used by classes which read images from database). So plz help me to use this method to read & write files using notepad but by using the abovementioned class/library. Thank u