How to load movie clips in library onto stage

I’m creating a site and when a particular button in the navigation is clicked I want to load the corresponding “page” movie clip onto the stage and remove any other “page” that is currently loaded. I would also like to have a nice alpha fade between them. I’ve been searching around and can’t find anything. I know this is simple like I need a loader container and I need to export for ActionScript the movie clips I want to load into the container. Just struggling to find the right code. Please help. Thanks!