There is much from which to draw upon for this question. I would suggest that chapter 5 might be a good starting point:
Napoleon, with the dogs following him, now mounted on to the raised portion of the floor where Major had previously stood to deliver his speech. He announced that from now on the Sunday-morning Meetings would come to an end. They were unnecessary, he said, and wasted time.
This particular quote reflects the dictatorship element that Napoleon sought in a couple of ways. The first would be the mere staging. Notice the "raised portion of the floor," indicating that there is a definite difference between he and the other animals. The idea of "some animals being more equal than others" is evident, setting the stage for his dictatorship. Additionally, the suspension of public discourse and his referring to such discussion as an example of "wasted time" also brings to the forefront the idea of a political setting where one person, he, makes the decisions for all others.
Another quote that could be useful for you to explore the issue of a dictatorship in the narrative would be in Chapter 8, continuing the idea of Napoleon's status being distinctive and more elevated than the other animals on the farm:
Napoleon himself was not seen in public as often as once in a fortnight. When he did appear, he was attended not only by his retinue of dogs but by a black cockerel who marched in front of him and acted as a kind of trumpeter, letting out a loud “cock-a-doodle-doo” before Napoleon spoke.
The idea of Napoleon not being seen in public is another example of the dictator element, as he does not need to be amongst the people as he is above them. Additionally, the "retinue of dogs" that accompany him help to consolidate his power, as they provide protection, savagely brutally demonstrated in the forced confessions element of chapter 7. (This would be a great chapter upon which to focus to demonstrate the real terror in Napoleon's rule.) However, in both presented quotes, the dictatorship theme is developed nicely.