How does the next paragraph end?

How to write an expository essay on an animal
Think of a topic.
The first step to writing a solid expository essay is to settle on a topic. As you already have animals as an overarching theme you'll need to specify further.
What animal are you writing about? An expository essay is an essay that provides the reader information about a particular topic. To write an expository essay on an animal, you'll have to choose an animal and provide a variety of information on that animal.