There are two parts to APA referencing: in-text citations and a list of references.
You must reference in your assignments. If you do not, it is considered plagiarism. You can lose marks and may fail the assignment.
You must reference when you use a direct quote (you must also put the quote in "quotation marks").
you paraphrase something you have read, by putting it into your own words.
you summarise what someone else has said about a topic and you include data, images, diagrams, etc. that you did not create yourself.
Basic Referencing Template
What is APA Referencing?
Referencing Images using APA7th edn.