In a traditional plot structure, there are seven steps or stages, as identified by the German writer Gustav Freytag. You may have heard of Freytag's Pyramid; it often looks like an isosceles triangle but missing the bottom line, with the seven stages labeled as the story figuratively travels up one side of the pyramid to the climax, or the top-most point, and down the other side to the story's end.
These seven stages or steps include exposition, or the revelation of any background information that readers might need in order to understand the story; inciting incident, the event that seems to initiate the story's main conflict; rising action, all of the events after the inciting incident that lead up to the climax between the protagonist and antagonist; the climax itself, or the moment of the most tension in the whole story; the falling action, or the action that occurs as a result of a climax; the resolution, in which the protagonist resolves their conflict; and, finally, the denouement, when the final strands of the story are explained.
The plot structure of "The Tell-Tale Heart" is nontraditional, ending immediately after the climax and lacking any falling action, the resolution, and the denouement. In the story's climax, the unnamed protagonist is overwhelmed by the physical effects of his own guilty conscience, and he confesses to the murder of the old man. This is where the story ends, and so we do not really know what occurs as a result of his confession or how the story is resolved.