Hello! In Steamworks, you can go to Technical Tools > Edit Steamworks Settings > Stats & Achievements > Achievements and add a new achievement. The first column, called API Name, is the ID for the achievement. This should be the same ID as you set when you make your Achievement objects in-game using the system. You can then add the locked/unlocked images in Steamworks as per usual. The only important thing is that the achievement has the same ID as the in-game one! Aside from that, the backend of registering and granting the achievement for Steam is all taken care of via the system. Hope that helps!