I don't really know how to explain this..

I use windows 7 platform
I make an application whose output is a file (consider *.asd). What I want to do is, if I double click this file, my application will run and open this file.

To simplify, I want to make my application's behavior like *.xls in microsoft excel. When I open *.xls file, microsoft excel automatically run and open this file.

Anyone got any suggestions?

Sorry for poor english