Astuce steam API avec un jeu

Bonjour, je ne veux pas traduire en Français ce que je souhaite faire, du coup j'ai copie collé ce que je voudrais faire ci-dessous

I am looking for developing a personal Java tool for retrieving lobby names for a specific game AOE2HD on Steam. I want to:
1.Retrieve currently logged in steam users who are playing this game and
2.The lobbies that are currently open where these users are waiting for others to join.

I looked into the steam API and so many other documentation online but I am not able to find currently logged in users or lobby details. I know it is possible because this website : [URL visible pour les membres Pro] does show this information. Does anyone knowledgeable in Steam APIs help me finding this information?

What I was able to do is to retrieve total number of (count) of users and achievements:

[URL visible pour les membres Pro]

[URL visible pour les membres Pro]

A couple of forums do talk about steam matchmaking apis but I am not able to figure out how to use it for this purpose.

Thanks in advance.