How can I get an audition for a role in a film?

Gee I wish it were easy to do, but it is not. First of all, all the lead roles and main supporting roles are cast without auditions by the producer simply offering the role to an actor he would like to have in the film. And should the actor not be available or not want the role, the producer has plenty of other people he will settle for. For example, the producers wanted John Wayne for the role of Dirty Harry, but he turned it down, citing too much gratuitous violence, so they wound up asking Clint Eastwood to do it and he said yes. These guys do not audition for roles, the producers send them scripts hoping they will want to be in their films. The same is true of the supporting roles. The producers ask known supporting actors of reputation, like Dub Taylor for example, to be in their films without auditions. By the time auditons are held for roles in the film,only the very smallest roles, one to five lines for the most part, are left, and you have to have an agent to get an audition for one of those and then you have to nail the audition. Well, that's the way it is done. Oh. How do some actors become overnight stars? First of all they have done a lot of very small roles and then some producer is impressed by their performance and asks them in for an interview and perhaps a reading. They get a main role and are suddenly an overnight sensation. Trouble is it probably took many years of struggling to get there. Exceptions like Robert Pattison exist, but consider he struggled for years to be an actor, was broke and living in his agent's flat when she convinced the producer of Twighlight to meet with him. Once in a while an agent is so taken with a talent that they will devote their career to promoting that one talent. That's a fantastic situation, but it is extremely rare. By and large asprining actors get roles in films via their agents. These roles are quite small,but occasionally some actors get noticed and move up. Most just fade away and become accountants or something.