A database is a collection of records, one for each item (e.g. a journal article, book, DVD), that is indexed. A record consists of elements of information about the item, called “fields.”

Common fields include: title, author, subject, publication, and keyword (all fields). You can obtain the record for an item by searching in one or more fields.
Here is an example of a record for a journal article and the fields by which it is indexed:

Once you retrieve the record, you will then see how to obtain the actual item.