Choose one paragraph from the story and argue in favor of its being the center from which the rest of the story emanates. You can look for a paragraph that represents for you the stylistic center of the story, or you can focus on a central setting, a central image, a central event, a central speech by a character, and so on. Once you have chosen your center, you will go on to Show how it functions as a hub for the story as a whole. You’ll be showing, effectively, how other parts of the story relate meaningfully to it.

In Kate Chopin's "The Story of an Hour," the social context of the narrative plays a primary role. The oppression imposed upon Mrs. Mallard by a male-dominated society caused her to suffer "heart trouble." 
A paragraph which acts as the central experience from which the rest of the narrative flows and ebbs is paragraph 11:

When she abandoned herself a little whispered word escaped her slightly parted lips. She said it over and over under her breath: "free, free, free!" The vacant stare and the look of terror that had followed it went from her eyes. They stayed keen and bright. Her pulses beat fast, and the coursing blood warmed and relaxed every inch of her body.

From the context of this section of the story, the reader can surmise that Mrs. Mallard is oppressed by her relationship with her husband. Rather than continuing to cry for the loss of her husband, as she appeared to do when she was informed of the unfortunate news of a railroad disaster in which he was purportedly a victim, Mrs. Mallard, who has climbed the stairs to the second floor of her house, relaxes in the privacy of her bedroom. Now Louise Mallard begins to enjoy the idea of her new freedom. No longer will she be under the dominance of her husband. Furthermore, any property that she has surrendered to her husband after their marriage will again be hers. Indeed, it is "a monstrous joy" that she feels in this "moment of illumination," in which no "powerful will" can impose itself upon hers. Louise recognizes her liberation as "the strongest impulse of her being." She continues to whisper to herself, "Free! Body and soul free!"
After reveling in this assertion of her new independence, Louise Mallard hears her younger sister calling to her. Josephine begs Louise to open the door. However, Louise wishes to delight in her new freedom more. Now, she "breathe[s] a prayer that life might be long," whereas before she "had thought with a shudder" that life might prove to be long. Then, just as Louise Mallard prepares to descend the stairs in her new triumph, "Some one was opening the front door with a latchkey. It was Brently Mallard." He was far from the scene of the accident and was unaware of it. Seeing him, Mrs. Mallard collapses and dies of what the doctors have come to term "heart disease—of joy that kills." In truth, however, it is the sudden shock of the realization that she again will be oppressed by her husband that her heart cannot withstand. The "monstrous joy" that she felt in her bedroom as she contemplated her new freedom has suddenly been taken from her. It is this loss that becomes the "joy that kills" Mrs. Mallard. Her joyous dream of being "free! free! free!" is abruptly ended.