How can I write a narrative essay consisting of an introduction, three body paragraphs, and a conclusion about the important events impacting the lives of characters in "Salvation" by Langston Hughes, "Sister Flowers" by Maya Angelou, and "What Suffering Does" by David Brooks?

It appears that you are being asked to write a five-paragraph essay in which you state a thesis or make general comments in your introduction, write one paragraph on each of the assigned works, and then conclude by showing how the body paragraphs support your initial claims. 
Your introduction should mention that all of these works are by twentieth- and twenty-first-century African American authors and all are autobiographical. They all deal with the intersection of spirituality, oppression, and the African-American experience. All of the works describe various possible paths in response to suffering.
In your paragraph about "Salvation," you should note that Hughes's narrative runs counter to the expectations of his community. Others in his community find religion a source of strength and solace, while the young narrator's inability to see Jesus is a source of sorrow. He will need to find his own path to some form of salvation.
In "Sister Flowers," the girl is slowly recovering from trauma, and while she has discovered reading, she is still uncomfortable with speech. Here, you might want to discuss how Sister Flowers helps the young girl reconnect to spoken language via art and think about how art and artifice can mend broken lives.
The essay by Brooks talks about how people are transformed by suffering. After a paragraph summarizing it, you could conclude by looking at whether his statements are true of Angelou and Hughes.  You could take as a starting point his statement:

Recovering from suffering is not like recovering from a disease. Many people don’t come out healed; they come out different.