Getting EXP level to be displayed in a scoreboard

Hello,
I am currently trying to make a plugin that displays players' EXP level (minecraft level) right under their nametags (the names appearing on top of their heads) but I am a total beginner in plugin making and I know almost nothing about the syntax.
I am currently trying to get the players' level data to be displayed in the scoreboard but I don't know how to.

Here is the code I have so far:

Code:

@Override
    public void onEnable() {
        s = Bukkit.getScoreboardManager().getMainScoreboard();
        registerLevelBar();
        //registerNameTag();
        Bukkit.getPluginManager().registerEvents(this, (Plugin) this);
    }
   
    @SuppressWarnings("deprecation")
   
    //EventHandler
    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent e) {
       
        e.getPlayer().sendMessage("HELLO THERE.");
       
        s.getTeam("blue").addPlayer(e.getPlayer());
    }
   
    public void registerLevelBar() {
       
        //Player p = e.getPlayer();
        //int plvl = p.getLevel();
       
        if (s.getObjective("plvl") != null) {
            s.getObjective("plvl").unregister();
        }
        Objective o = s.registerNewObjective("plvl", "plvl");
        o.setDisplayName(ChatColor.AQUA + " lv");
        o.setDisplaySlot(DisplaySlot.BELOW_NAME);
    }

Any thoughts?

 

@Wirexin What are you having problems with?

 

The point is, it doesn't work at all. Nothing shows up and I am not %100 sure what I did wrong I need some handholding level guidance here

 

@Wirexin I haven't worked with scoreboards a lot but, don't you need to set the scoreboard using Player#setScoreboard(Scoreboard)?

 

How do I even implement this ? Also are you sure I got the level variable right ? I think the issue could be because it cannot reach the level variable from the player.