1) You can write a traditional outline (see the "En contexto" page for an example of what Francisco wrote)
2) You can create a storyboard, like what we did in class.
The storyboard is a way to tell your story using pictures, with a short sentence to explain each picture. Start by drawing pictures to illustrate the main ideas of your story, then write a sentence in Spanish for each picture to describe what the picture is communicating to your reader.
The outline/storyboard will serve as the basis for your rough draft.