The mcMMO API is a new utility to mcMMO. It is used with the new events system, to make it easy.

The basic syntax goes like this:

package packagename;

public class MyListener implements Listener {

  public void onPlayerLevelUp(McMMOPlayerLevelUpEvent event) {
      Player player = event.getPlayer();
      SkillType skill = event.getSkill();


That would be your Listener class. Now, you just add this line into your public void onEnable():

Bukkit.getServer().getPluginManager().registerEvents(new MyListener(this), this);

From there you can extend and add more features. :D