Hmmm, how did you get to the brave yard without opening the door? Methinks cheating has occurred.

anyway, opening the back door is quite a lengthy process, so hang on.

1: Go to the Library and pick random books until you get the rain dancing book.

2: if you read the book, you will be told to surround yourself with water and go for the highest sound, so take the book to the swamp and then use the dog whistle you got from the professor for catching insects, it will then rain.

3: now, catch the frog in the swamp and return to the church.

4: you need to stop the lady playing the organ, but using the frog on her only causes her a litle scare, so use the stinky potion the professor gave you with the frog to make a mutant frog and use it on the lady to frighten her away.

6:Now to play the organ, accept, it breaks and needs to be fixed.

7: go to the library and hand over the book on hermiting to get a book on organ repare.

8: return to the church, take the organ key from the organ, use the book and then use the key with the organ.

9: if you use the organ you'll find it has four tones you can play, head to the swamp and give the bubling potion to the hermit, it will cure his problem and he'll give you some peanuts.

10: Head back to the pet shop and give a peanut to the parrot, memorize the litle tune the parrot sings then go back and play it on the organ in the church and the door will open.

As to the tones in the grave yard, I'm afraid that the combination is random, and if you don't guess it within a certain umber of tries the lock will close and it will change again, the only way out of this puzle I believe is logic.

I hope this helps.