Creating the Backstory for Your Screenplay (Dummies.com):

Most writers dream a little before they tackle writing their scripts. Actually, they dream a lot. Before you craft an environment, you want to know its history, its geographical location, and its condition. Before you write a scene between parents, you want to know what attracted them to each other, how long they've been together, how many children they have, and the like. Before your characters go to war, you have to know what moments in political history led them to that battlefield.

Developing an Artistic Sensibility for Screenwriting
(For Dummies)

Crafting Your Character's Dialogue in Your Screenplay (For Dummies)

See all of Acting and Filmmaking for Dummies

Also see:

Writing Poetry for Dummies

Snuggling Up to the Language of Poetry for Dummies