One of the common ways to edit a bibliographic record or your holdings on that record is to search for the record.
When you click on that record, You see a screen that might be similar to this:
This screen actually has two parts.
The top part has information about the bibliographic record.
Just below that you see a number of tabs – “OPAC View, MARC Edit, MARC View, View Holds, etc.”
This lets you choose one of several different ways to work with this record.