Movie

I went to see a movie tonight. It was a scary movie called Joker. The main character is a clown. He has a mental problem so he couldn’t believe people. It was a sad and scary movie.

I agree with Zenny's corrections below; however, I did want to point out the use of the phrase, "mental problem" in English, especially regarding American culture (if you are using English somewhere else, then feel free to disregard this message). If you say "mental problem," it could be taken offensively. A better approach would be to say, "mental health issue." This is more accepted, at least in American society. The sentence would then read, "He has a mental health issue, so it was difficult for him to believe people." You'll notice I also changed "he couldn't" to "it was difficult." This is again a cultural difference and is a way to communicate that you have empathy for the character.