Move the keys to the middle in the order of the symbols. Each one will show a letter. Move the dial to the letter. Once you have done all seven keys, the door will open. I'd say more, but I don't want to spoil the ending for you.
How good Karmyn to find your answer. I have been playing this game a couple of days now, and after having found all the keys I had not time enough to find out how to open the door. Next time maybe I can. Thank you, Christina