Create the Main Class of Your Mod

Create a new class in your mod package that implements MModdingModInitializer:

MyMModdingMod.java

public class MyMModdingMod implements MModdingModInitializer {
    
    @Override
    public Config getConfig() {
        // We will keep this value as null for the moment
        return null;
    }
    
    @Override
    public List<ElementsInitializer> getElementsInitializers() {
        List<ElementsInitializer> elementsInitializers = new ArrayList<>();
        // Check the "Use ElementsInitializer" page
        return elementsInitializers;
    }
    
    @Override
    public void onInitialize(AdvancedModContainer mod) {
        mod.getLogger().log("Hello MModding World!");
    }
}

You must replace MyMModdingMod by your mod's name following the Java Naming Conventions!