how to properly use classes in java code example

Example: using class in java

public class HelloWorld {
  public static void main(String[] args) {
    
    // how to use class in java
    class User{
    	
    	int score;
    }
    
    User dave = new User();
    
    dave.score = 20;
    
    System.out.println(dave.score);
    
 
  }
}