For now, there's no way into the pirate cave. For the ghost book you just need to spend some time reading it in the closet - if you don't know what to do after that you might have to fail a pact at the temple
Byt what does "if you don't know what to do after that you might have to fail a pact at the temple" mean what steps do we have to follow so we can see what the atlas does
Get the book, go to the closest, stare at it. You’ll get the magic word elsewhere when it happens, that is all it literally does, but you will need to fail the pact and then the option is available for the Atlas to become useful… Hope this helps!
