The exposition for Things Fall Apart is Achebe's description of the character, achievements, and background of Okonkwo and the ways in which he symbolizes the best and the worst of the society from which he comes.
The rising action tells the story of Okonkwo's guardianship of Ikemefuna, the way in which he is forced to kill the boy against his will, and the effect this has on him.
The climax comes when Okonkwo's gun explodes at Ezeudu's funeral, and he is exiled to Mbanta for accidentally killing Ezeudu's son.
The falling action is the longest section of the novel, as befits the title. It chronicles the steady decline of Umuofia and the increasing power of the white men who have arrived in the region. The local people, including Okonkwo's son Nwoye, begin to embrace Christianity. When Okonkwo returns from exile, he reacts with anger and violence, waging war against the white interlopers.
The resolution comes when the district commissioner discovers that Okonkwo has hanged himself to avoid the indignity of a trial. He muses on this incident, which he does not understand, and resolves to record it in a book he intends to write.