You can identify books to add to a genre by creating a Resource List from the catalog or physically pulling the books from the shelves to scan.
Option 1: Resource List
Go to Catalog-Resource List-Add List
Give the list a name of the Genre you want to add. You don’t need to make this list public.
Go Back to Library Search and do a search for the books to add for your genre list. Keyword should find most of the results or if you know the specific books, look them up! Click to add them to the list.
Once your list is complete, go to Catalog->Update Copies->Batch Update