By reading your explanation of the problem, I am to understand that you have all things needed to continue except for the 3rd part of that Symbol. To get it, use those ritual books you have, and study for the exam that the statue gives you. He asks about the Morning ritual, and if you read the ritual, then you can answer correctly. He follows with the afternoon, and the evening. Then you will be given the last part of the symbol to open the door.
(Remember that the Shadow Dragon Wardstone will protect you from the dragon when you eventually meet up with it, like the person who gave it to you mentioned. You can still fight, though, if you throw the first punch.) I would recommend coming back when you are stronger...he'll still be waiting for you.
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