This is a short story so you should be able to re-read it to verify this answer...
The way to identify the climax of a story is to find the point everything else in the story is leading up to. After that point the rest of the story changes.
For this story--By the middle of the plot Tom has become a loan shark and is constantly cheating people out of money. Eventually he becomes fearful for the after-life. (this is leading up to the climax--hinting at a problem to come) He then starts to become fiercely dedicated to God, always keeping a Bible at hand. One day, a person who had borrowed money from him and is asking for mercy blames Tom for taking his money. Tom says, "The Devil take me if I have made but a farthing!" (this is right before the climax)
CLIMAX POINT--At this time, there are three loud knocks at the door. Tom is drawn towards the black cloaked figure and realizes, in horror, that he has left his Bible at his desk.
RESOLUTION--Tom Walker is then taken away by the Devil on the back of a black horse and is never seen again. All his assets vanished and his house burned to the ground. The ghost of the miser - haunts the site of the old fort.
The resolution is just the end of the story where all the loose ends are tied up. Basically "what finally happened"