There are two basic methods for conducting searches. Keyword searching looks for the exact form of the keyword somewhere in the record. Subject searching also uses keywords, but the subject headings assigned to a source depend upon a classification of the source's content that has been determined by the database and that employs a limited vocabulary of possible subject terms. You should start with keyword searches using terms and synonyms that occur to you and that might potentially show up in the title of a source. In many databases, basic keyword searches will also look in the "subject" field for a match. But to maximize your chances of finding sources with relevant content you will also need to determine what other subject headings the database uses for classifying your topic. These headings vary from database to database.
Click this link for advice about how to identify useful keywords.
Click this link for advice about how to identify subject headings in different databases.