How to make my special exitintion intgreating with my program

You should once double-click on your file and in windows "file open" dialog select "Open with" – and point to your program. Check the checkbox "Always use this program" – so your program will be registered for such extensions.

And, your program will receive the file part in parameters args:

static void Main(params string [] args)

So you can use it for real file loading and displaying or something else.