History is all about evaluating and critically analysing events and historical happenings. Including historiography in essays is very simple - you only need include an idea and the name of the historian or school of thought who wrote about it. You can find such ideas in all of your history textbooks.
Firstly, it is useful to familiarise yourself with the different schools of thought. For example, there are orthodox historians who generally write at the time of the event up to 10 years after, and are the first school of historians writing and analysing that historical event. Next, there are revisionist historians writing around 2 decades later and revisiting the event from a new point of view - for instance, US revisionists took a new stance on the Cold War in the 60s due to US involvement Asia, particularly in Vietnam. Finally, post-revisionists essentially reconsider revisionist writings and form new opinions based on emerging evidence and naturally great hindsight. In the Cold War example post-revisionists would be writing in the 80s/90s era after the collapse of the Soviet Union.
Once you have identified different schools of thought, it is helpful to look at your textbook. The IB textbooks always include several quotes from historians to illustrate a particular viewpoint or analysis. When writing your revision notes and essay plans, always incorporate such a quote or idea after evaluating and explaining the facts. It will show the analytical skills essential to attaining a grade 6 or 7. It is helpful if in your notes you write such ideas in a different colour, to make them stand out, and in your summarised notes after the facts and details you will always find some historiography to match the event.