griiiy

Hi everyone , I'm a new starter of this game and really enjoy it . I play as a Roman , and now I just finished my first task. Then I reached the ruined hall , and found a faerie in there. That faerie told me there are some massages in the dungeon I should take. So I came to the dungeon , finally I found a door with three oval-shaped hole. It says put some stones or anything in could open it , I picked rocks on the floor and came back to that door , but nothing changed. And here comes my question. Do I have to do something with my rocks?What should I put in that hole ? And if I have found something uesfull, what exactly should I do or I just walk to the door?