A lot of people write by the seat of their pants—that is, they rush headlong into writing a book without any sort of physical outline. That’s okay. Everyone’s writing process is different and if throwing yourself into a story without an outline works for you, there’s nothing wrong with that.
Stories are organized around a sequence of events that contain plot drivers that influence what happens in that section. Throughout time, storytellers have drawn upon common story structures that have evolved within their culture.
In most stories, your protagonist wants something—to change a law or the government itself, to avenge a death, to hook up with the cutie, to dispel a curse—and your antagonist usually wants something that is in direct opposition of whatever the protagonist wants.
"Exposition" can be a scary word. In some writing circles, "experts" will warn you to exercise extreme caution when using it, or they'll make it out to be a difficult but necessary evil. But ultimately, exposition is just another writing tool, and it's used in all sorts of writing, even beyond fiction.