The main conflict in this story is between Tris and the fact that she has a secret she can't tell anyone. This is because, in her situation, it would be dangerous to tell anyone. This is technically a man vs. man conflict. A major man vs. man conflict later develops between Tris and Jeanine Matthews.
One example of a rising action in the story Divergent is when Tris finds out that she is Divergent; a mix of two or more of the five factions. This is a dangerous situation because everyone in the society must belong to one faction.
A second rising action in Divergent would be that Tris makes the bold decision to be a part of Dauntless. It is said that changing factions brings shame upon your family, but Tris did not care. She did what she wanted.
The climax of the story is when, after initiation, everyone is injected with a serum. The only people who are able to resist the serum are the Divergent. This means that Tris and Tobias-the man she loves-are able to resist it, but they play along in the brainwashed state everyone else is in.
The falling action of Divergent is when Tris escapes her execution and takes her father, brother, and Marcus Eaton and runs back to Dauntless headquarters to stop the simulation. Little does Tris know, Tobias is controlling it under his own simulation. Tris eventually gets him out of it because he realizes he loves her, and together they stop the simulation.
This, however, would not be the end of their struggles. It is only the beginning of the "war" against Erudite. Tris, Marcus, Tobias, and Tris's brother escape on a train to go to Amity headquarters.