How do the monkeys that the group encounters in the hill country serve as a plot element, to advance the story?

While Lahiri stresses the social contrasts between Mr. Kapasi and the Americanized Das family, the most focal clash in the story is the inward clash inside Mr. Kapasi. There is an error between the way he sees himself and the way that he really is. After Mrs. Das demonstrates an enthusiasm for him, Mr. Kapasi starts to fantasize about comparing with her and in the long run building up a private relationship.

You could start by introducing the concept and give a quick rundown of it. Once you complete doing that, slowly continue on, about your position on the topic. Finally, get to your point on the topic and write more into the specifics of the topic and in much greater detail, then finish up with another quick run down of the topic.