There are four parts to every story 

Part one: Someone wants something

Part two: Someone goes on a quest

Part three: Someone is rivalled

Part four: Someone gets what they want

Part One: The Wants

For a character to be human they must want something. That 'thing' tells us the characters personality and makes us root for them. Like if a character wants friendship or freedom or adventure or to belong or maybe they just want an object. That tells us what kind of character we have and whether or not we like them. It is the most important thing about any narrative.

 Part Two: The Quest

Now the word 'quest' is pretty arbitrary. What I mean is that someone in a story must seek out what they desire, whether it be friendship, love or an object. Or it could be something deeper though, like wanting to be accepted so the 'quest' is them reaching out to people. You decide. 

Part Three: The Conflict

Every story has to have some form of conflict. When a character goes on a 'quest' to find the thing they want they usually come across someone or something that prevents from getting it. This is their rival. The antagonist. They must defeat their rival before obtaining their goal.

Part Four: Victory! 

After all their hard work the main character gets what they desire. This is where the story ends and the curtain closes. The ending is the WORST part of every story. It should make the reader sad that it's over and leave them wanting more. 

My sister mentioned that characters don't have to get what they want. They could fail completely at the end. Which is also a possible route. Stories don't have to have happy endings. Have you ever read 'the boy in the striped pyjamas?'