Hey!
Thanks for downloading - its great to hear you're keen to run it!
Unfortunately im not aware of any tutorials on how to play. However, as this is an OSR style 1 page dungeon, its intentionally vague on a lot of the details, and gives the GM the freedom to inject their own ideas.
To answer both your questions for example, firstly I interpret the dice numbers in front of the monsters as a suggested number of them that appear when drawn. So d8 means you could roll a d8 and use that number, or just pick "4 appear".
The door in the courtyards is am obstacle for the players to overcome. There plenty of ways for them to do so, perhaps you decide a key is on the corpse of one of the skeletal monks, or one of the grave robbers found it. Perhaps the players can pick the lock, or break it down, etc. That kind of a thing.
I hope that helps!
- Olobosk