ALWAYS follow instructions given by your professor.
APA Style is a set of rules and guidelines compiled by the American Psychological Association to create consistency in scholarly writing and guide writers in proper citation of resources.
Bookstore link to purchase the Publication Manual of the American Psychological Association. https://www.bkstr.com/gahighlandscarterstore/product/publication-manual-of-apa-715950-1
The Manual is a full list of rules, and should be referred to when you have detailed questions.