Great question! There are multiple answers to this question, so I'll elaborate on the main events in my view.
The story begins with our protagonist, Tom Benecke, regretfully choosing to stay home to work on a special innovative project for his job rather than go to the movies with his wife. When she leaves, the door closes behind her, blowing a paper vital to his project out the window. Horrified, he rushes to the window, only to see that the paper has gotten stuck on the ledge near his window, far from reach and hundreds of feet above the ground.
This is the first conflict of the story. Impulsively, Tom decides to climb out onto the ledge and risk his life to try and get the paper back. At this point in the story, we have to wonder why a straight-laced guy like Tom would choose to do something so dangerous. Our answer is provided for us in the story, as Tom describes (to himself) the "countless hours of work" he spent creating this document, and how without it, his innovative idea was "mere opinion." The emotional investment Tom made both in this document and in his work ambitions combined to create an irrational and near-fatal decision.
Tom climbs out onto the window ledge, trying desperately to numb his mind to what he is doing. The second conflict and the climax of the story occur here. Once on the ledge, he inches toward the paper, but after a terrifying close call, he completely freezes up. Hanging onto the ledge, he's forced to contemplate his regrets. Above all, he wishes he had just gone to the movie with his wife, where he would be safe and warm. He doubts that he can hang onto the window until his wife comes home. Realizing that he'll have to break a window to get back into his apartment, and that using that level of force without success could drive him backwards off the ledge, he opts to take his chances. Not knowing whether he'll succeed or not, he hits the window as hard as he can. He manages to break the window, and tumbles through into his apartment.
Through these several suspense-packed minutes, Tom has undergone virtual years of growth. He realizes that his real priorities are his own life, pleasure, experiences, and his wife. Once back in the apartment, he leaves to go find his wife at once. He leaves the paper on the table once again. As he closes the door to leave, it symbolically (and literally) blows out the window "and out of his life," prompting a burst of near hysterical laughter from Tom. He has realized that in the scheme of things, he knows now what he values, and it's definitely not this project or that paper.