Adding Books to Nook HD using Android File Transfer

[Microman]

Have my Mac and wifes Nook HD.

I have been copying books (epub) to MY FILES --> BOOKS and PDF's to MY FILES --> Documents.

IS that ok, or should I just put everything in Documents?

Thanks

I have to reformat to original, and reinstall books, as I have two covers that are no book to launch, and no way I have found to delete the covers.