What do you find funny? What kind of humour are you looking to create?
Trying to write a humorous short story can be very difficult. Humour is more difficult than drama, requiring a different set up and a twist. Whether humour is in music or prose, it is often the mild surprise that strikes us as humorous.
If you are looking for a dry wit to leaven an otherwise heavy story, create a character with such a turn of mind and have him observe these situations that he finds ridiculous.
If you want something that is humorous, read the works of O. Henry. They are memorable for their twists and have a gentle humour and irony to them. See how he did it and then look at examples of stories that you find funny. How did the author do it? Were you led to expect Y when X happens? Is it purely diction?