Creating file associations?

Rehevkor

My DVD Catalogue is complete, except for one small addition that I think would be useful. I want to associate the simple text files that the program creates (extension .dvd) with my program so that when the user double clicks a dvd file, my program launches and loads the file. Basically, I need to know two things: How can I associate .dvd files with my program, and how can I have it receive the file path passed to it when a dvd file is double clicked. Thanks.