system
Given the following post, respond as if you're commenting on Reddit:
human
[ELI5] Stanley Kubricks "The Shining".

 There are a lot of things I don't understand about this film. I do understand the kid had a psychic ability, and sort of predicted what was going to happen. 

I don't get the scenes where Jack is at the bar, the last scene of the film where it shows him as head guy of the hotel and the hallucinations  Wendy was having during the end of the film.

Thanks a lot.
gpt
Kubrick used the book as a jumping off point. There was a lot of things that he changed to make the kind of movie Kubrick is known for making. The novel does a better job at answering your questions. 

The Hotel wanted the power to get people to do what it wanted. The Hotel had a little power over most people. It could plant thoughts in people's heads. The last one the Hotel had got to was Delbert Grady's daughters. They had  a small amount of psychic ability, or "The Shine." Because of this, and because the girls were killed in the hotel, their Shine could be used by the hotel to get in the Torrence family's head. Jack was the easiest one, because he was an alcoholic. All the hotel had to do was make him think he could get drunk and he would do what the Hotel wanted. Jack was only trying to get drunk and still have a way to support his family. So the hotel made the bar seem like it was a fun place to be. The Hotel also offered him the caretaker position forever. Jack, when he was drunk, thought that was a great deal. 

It was a lie, but Jack didn't know that. The Hotel only wanted Danny, because Danny was the strongest Shine that had ever been in the hotel. When Jack is in the bathroom with Grady, Jack agrees to get Danny to work for the Hotel, he says that he can take charge of his family. He fails, because Wendy is stronger than he is. 

So, the Hotel uses Wendy and her love of Danny to get her to work for the hotel. If the hotel can get her to kill Jack, the Hotel may get her to kill Danny. At the end, that is why the hotel is showing her all these things. It is only to scare her enough to make her want to kill her husband. 

Jack becomes the caretaker in the final photograph because he did what the Hotel asked him to do. The hotel gave him that part of the promise.