Okay, first off the support documents on the Board of Studies website are more designed for Section I of the course; 'What is History?' rather than the case studies. Okay, I'll just copy /paste what the syllabus states for the JFK Case study (primarily focusing on this individual one as it's the case study I'm doing, and the most popular in the History Extension Cohort).
Option 20: The Nature of the Presidency of John Fitzgerald Kennedy
Principal focus: students investigate changing interpretations of the evidence relating to the nature and achievements of the presidency of John Fitzgerald Kennedy.
Students examine the approaches to history and interpretations (including recent historiography) that have resulted in historical debate in the areas of:
– representations of Kennedy – man and myth
– public and private figure
– role in the Cuban missile crisis
– Indochina
– relationship and dealings with Khrushchev.
So basically you're looking at the conflicting approaches and Historiography to those five dot points, or debates. So you'll want to have studied those points in depth, and have an embankment of sources and Historians' perspectives for the exam. Generally in the exam, there will be given a source; which you will have to apply to one (or perhaps two) areas of debates, and thus incorporate the source and different Historiographical approaches to the debate.
I'm guessing you're in the same position as myself, my class has finished studying the first section 'What is History?' and then did some work for the project during lesson time. And now only are starting the case study. Best not to worry too much, there's still plenty of time to ask your teacher when school resumes, and they'll be able to make more sense than what I just attempted to.
Anyways, best of luck n_n. Don't stress out too much, there's still time before doom.