Introduction
Introduce the TOPIC and REASON for writing. So, name, date, main idea, storyline of the film, etc. (NOT in too much detail, though.)
Main part
Decide which elements you'll discuss, tell them what is GOOD and what is BAD.
Tell them WHY it is BAD, tell them how to FIX the BAD, or at least point them in the right direction.
Conclusion
Give a CONCLUDING SUMMARY and recommendations/call to action.