Tip for: 10.17.16
...to this, where you can view the MARC tags for this item.
Unlock the record, click on any tag, and you will be able to add subfields for that tag and add new fields.
The 6xx tags are where you’ll find subjects, and authors are in 100. To learn about any tag, click on it, then click Read About This Field, which will take you to the Library of Congress website for MARC Standards.