In the beginning of the novel Montresor is thinking about revenge on Fortunato and he is planning how to make him suffer. Montresor wanted his revenge with impunity.
The rising action and conflict would be when Montresor took Fortunato to his house by tricking him to come and see the Amontillado by saying Luchesi was going to see the amontillado instead. They are in the carnival.
I finally got my revenge on that Fortunato!!!
The climax took a while because Montresors impunity of revenge wants to last for centuries. He took Fortunato down deep to travel between the bones and to the vault were he has the amontillado. They left the carval and went to Montresor house.
The Falling action would be when Montresors started building the wall and blocking Fortunato in the vault with cement to kill him slowly.
Montresors got his revenge on Fortunato with impunity but he can't tell no one about it. Montresors feels relief about the what he did to Fortunato.