The assignment is "open-ended" except for the first sentence, which should read something like this: "In Cynthia Kadohata's novel kira-kira, the theme of ______________________is explored in subtle ways. For example...." (You can also use other transitions--signals to the reader of the direction your thoughts are taking-- to your illustrations. You might choose to use "For instance" or "This theme appears at the very start of the novel when....")
The goal here is to lay out a general evaluation of one of the book's key themes (Reader's choice of theme). Then pick at least two instances in the book where the narrator's (person telling the story) thoughts, characters' behavior, or descriptions of dialogue and setting reveal how the author is trying to make readers think about the theme you have introduced in your opening sentence.
There is no right or wrong choice of theme here. If you say it's in the novel and can support it with descriptions of incidents in the book, then the theme exists. What's really important is that the thoughts, dialogue, or events you describe match the theme you mention in the opening.
I'll do a post in the next 24 hours from a book I'm reading called Oleander Girl. In it, I'll follow the template, or pattern, described here, so you can get an idea of how your post should read. I think that will clarify what I'm asking you to do. But if it does not, you should e-mail me with questions.