The plot is the story's foundation, and the resolution is the ending element. So if the story has a mystery that needs to be solved, the resolution is when that would take place. For example, if the good guy needs to be rewarded for his due diligence--or the girl still hasn't gotten the guy--the resolution would provide their fate. The resolution is the final curtain call of the story; it will usually happen very quickly and is also known as the "denouement" (see References below).
Every story has a series of events that happen in chronological order. The climax and the resolution are closely related, and they happen toward the end. The climax is the high point of the story (e.g. a battle, confirmation, revelation, catharsis, etc.). Once the climax has been resolved, the story can end (see References below).
The resolution also conveys the destiny of characters. When an audience is invested in the plot of a good story, they want to see it through to the end. In some cases, the audience may be sympathetic or empathetic to certain characters. Other viewers may be rooting for the underdog to win or waiting for the bad guys' demise. The resolution of a story is an intricate part to the narrative because it provides closure for the audience (see References below).
When you write a resolution, you should attempt to create a character your audience will genuinely care about. If the plot can cause the audience to acquire feelings for your character, (even if the character's circumstances are new to them), then they will also care what happens to the character. Even if you want your main character to be hated by your audience, they will still want to know his fate. Creating a character that really engages your audience will make for a successful resolution (see Resources below).
When writing a resolution, you will garner the best results if your character is pursuing a particular goal. If the character has an objective, you can shape the plot of your story around accomplishing the goal. For example, your main character may be a stay-at-home mom. At the beginning of the story, she loses her husband in an accident, and she needs to find a way to fend for herself and her children. The resolution could be the "stay-at-home mom" finding the resources to take care of her family (see Resources below).