1. Find the pattern with the numbers on the candles in each row: 1 2 3 4 6 4 5 6 7 8 6 5 6 9 4
2. The first ? for row 1 is 8. The second ? for row 2 is 9. The third ? for row 3 is 1. (this I got from just scrolling through the number after the first two) Pick up the key and use it to open the door.