1. Get an idea for a plot. 2. Make up character names. For example, Trixie and Bibi. 3. Write out their lines and basic plot elements.
Like this: (Cars zoom by. Trixie and Bibi are walking and talking. Bibi looks pained.) Trixie: I don't CARE what Tom said, it's not true. Bibi: But he said it so-- Trixie: (etc etc)
Or like this: (camera slowly zooms out on the tombstone.) Bibi: (sobs)