I have a few questions regarding Zelda?

IN OoT, how do you enter the Sacred Rehlm? I know you need the 3 Spirtual Stones to get to the Sacred Rehlm, but all they do it open the Door of Time. But inside the room that the door opens to, itsnt the Sacred Rehlm. How do you get to it??? And im not asking for a walkthough or anything. I know its not up to you when you can vistit the Sacred Relhm or not. I have beatin the game. I just wanted to know how Link got there.