I'm litterally copying somones answer but I still get this weird error.

./Main.java:16: error: cannot find symbol
    forum.addPost(post);
         ^
  symbol:   method addPost(ForumPost)
  location: variable forum of type Forum
Note: JavaTester.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error

public class Main {

  public static void main(String[] args) {
    System.out.println("Beginning forum example");
    if (args.length < 2) {
      System.out.println("Usage: java Main <first name> <last name>");
      System.err.println("<first name> and <last name> are required");
      System.exit(1);
    }

    Forum forum = new Forum("Java");

  User author = new User(args[0],args[1]);

ForumPost post = new ForumPost(author, "TestTitle", "TestDesc");
    forum.addPost(post);





  }

}