Paragraph 1: Hook your readers, make us interested. Give us the background information of the film: what is the setting? Basic plot? Let us know your basic opinion of the film.
Paragraph 2: Go into more details. How do the setting and plot relate to the theme? What is the theme? Provide some evidence of why you feel the way you do about the film. (You should give at least 3 examples of evidence related to your opinion. Don't just tell me the film was awesome, explain your opinion by describing what makes it awesome. Cite specific examples from the film.)
Paragraph 3: Sum it up. Restate your opinion, and urge your audience to either see the film or avoid it based upon the evidence you supplied in paragraph 2. Give your audience a final thought.