A stranger arrives in Red City. He crosses the main street on a horse and stops in front of a Saloon. He slowly comes in and all eyes are directed at him. He's the new sheriff, but noone knows it, except for the director. There's a sinister-looking man that teases him, but he ignores him and, once he teases him again, teaches him a lesson he won't soon forget. At this point, we all know who he is.
Within two minutes the saloon singer, who is engaged to Joe, the owner of the joint, falls in love with the new sheriff. It turns out Joe is actually the chief of a gang of cattle robbers and, soon enough, he's unmasked. When that happens, he grabs the girl hostage and makes a run for it. An insane chase ensues. The sheriff takes a short-cut and hides behind a rock, from where he jums on Joe, knocking down the horse. After a longwinded struggle the sheriff, wounded, manages to disarm the bandit and the fight ends when the outlaw is pushed off a cliff and dies.
Soon after, the sheriff triufally returns to the city, where he finally marries the singer. After a joke, a moralizing remark and a couple of gunshots, they both disappear into the sunset on their horse, while the theme song softly plays. I'm a poor lonesome cowboy bla bla bla...
You start by choosing a renowned person: a politician, painter, scientist, anyone of these will do... What's important is to choose a little-known aspect of their life, that shows their humane side. The ideal would be a love story. If said person was celibate, Hollywood's love story department will certainly cook something up. Oh! It's essential that the leading role be played by a very famous actor, the likes of Marlon Brando, Al Pacino, etc.
Afterwards, you create an atmosphere of the era, in the appropriate studio, with sophisticated wardrobe and props. This is relatively easy. You only have to be careful in the outside scenes to make sure no cars or airplanes show on camera, like in Ben-Hur. If the editing crew is careful, everything works out fine.
The rest is even easier. The famous person spends the entire movie fighting for his talent to be acknowledged, which only happens at the very end (what do you think the scriptwriters are, stupid?). It's important that one of these situations happens in the end, though: either his success is due to his partner, that always believed in him; or he has to leave her to follow his personal dreams. The public usually likes each of these two happy endings.