It sounds like you are filling out a plot diagram for the short story "The Landlady." Check out the video linked below for more on plot diagrams. As a quick review, plot diagrams are a visual representation of the plot of a story. As the story starts, you have the events of the exposition, or the explanation of who the characters are, where the story takes place, etc. The exposition ends with an inciting incident or complicating incident - something that happens that will change things for the character(s).
In "The Landlady," the complicating incident would be when Billy Weaver, looking for a place to stay the night, is compelled to ring the bell at a bed and breakfast, even though he had just made up his mind to stay at the pub instead. The story describes how the "Bed and Breakfast" sign pulls Billy in:
"Each word was like a large black eye staring at him through the glass, holding him, compelling him, forcing him to stay where he was and not to walk away from that house, and the next thing he knew, he was actually moving across from the window to the front door of the house, climbing the steps that led up to it, and reaching for the bell" (paragraph 11).
This is the complicating incident because this is when the story takes a weird turn. Up until now, Billy was just an ordinary young man, with an ordinary job, looking for a room. Now there is an element of intrigue, of danger, even of the supernatural.
After the inciting incident in a plot diagram comes the rising action. These are the series of events that up the main conflict. In "The Landlady," events in the rising action would include the landlady having a room ready for Billy, Billy reading the names in her guest book and trying to remember them, etc.
The events of the rising action lead up to the climax of the story – the point of greatest excitement and interest for the reader, when the conflict will be decided, one way or another.
In "The Landlady," the story structure is a bit unusual. One would expect the climax of the story to be when Billy figures out that the landlady is poisoning him and plans to keep him in the house forever, like the other two men in the guestbook. Incredibly, Billy is so naive that he never appears to realize his own fate. I would argue that the climax is when the reader knows for sure that this is what will happen, which of course depends on the person reading the story. It could be when the reader learns that the landlady has stuffed her dead dog and parrot. It could be when Billy notices his tea tastes a bit like bitter almonds (an indication of cyanide poisoning). It could be the final line of the story, when the landlady admits that she has had no other visitors in the last several years. It really depends on when the reader figures out what's going on.
Your final question was about the theme of the story. A story's theme is the universal message or idea that runs through the story. It's often what the author wants to say about how the world works. One theme for "The Landlady" could be Youthful innocence is easily deceived. Billy, after all, is only 17-years-old, working at his first job. His narration suggests how young and easily impressed he is when considering his older coworkers:
"Briskness, he had decided, was the one common characteristic of all successful businessmen. The big shots up at the head office were absolutely fantastically brisk all the time. They were amazing" (paragraph 5).
Billy's wonder about the world and easily-impressed nature continues throughout the story, as he reacts to the increasingly-alarming statements from the landlady. Even at the end of the story, having drank poison tea and been told that the landlady performs taxidermy on her dead pets, Billy's predominant emotion is still admiration: "'Good gracious me,' he said. 'How absolutely fascinating.' Thus his innocence is taken advantage of by the malicious landlady.
For more on the theme(s) of the story, check the link below!