Whether you're writing fiction or nonfiction, your story needs a plot.
The plot is what pulls the reader through the story. In fiction, you make up the events of the story based on the motivations of your characters and lay them out in an order that makes the reader want to know what happens next. In nonfiction, you detail the events and examine the motivations of the real people about whom you're writing to come up with a story that makes the reader want to turn the page. I have shelves filled with books on plot and have used several different methods to come up with the plots in the books and short stories I've written.
Recently, I took Holly Lisle's Plot Outline Course and found it very helpful.
Go here to read more about the other Holly Lisle courses I've taken.