Scenes organise a movie into categories.
For example, one scene can be for the preloader and another for the introduction. If you were a company you could also create scenes for your contact details, projects, credits etc. A basic Flash movie which contains two or more scenes will play back one after another, in the order that they are listed in the Scene inspector. To make your movie more interactive and 'jump around' like I mentioned before you should use actions. The use of actions like Stop, Goto and Play in your movie will add an element of interactivity and allow your visitors to move around your movie like a web page.