you take a minor character from a film that already exists and you make them the main character in a movie of your own.
I'm not going to tell you the details of how you make it, but basically, when all is said and done you set up 2 dvd players next to eachother and two tvs next to eachother and you press play on the old movie and your movie at the same time. If you did a good job, then the main character in your film will walk offscreen and walk right into his minor role in the previously existing film.
man, you will be so cool then.
You don't need to thank me.