What is a scholarly resource (and why is most online material unsuitable)?
What is a complete reference?
The Box Hill Institute style of Harvard referencing is described in detail at http://libguides.bhtafe.edu.au/referencing
In a degree course you're learning how to take your place among professionals.
You're learning new ideas, new words, and how to start with and follow through your needs for more information. If you take information and copy it, you're not demonstrating your ability to do this.
Sometimes the best information will include the local and community knowledge you've grown up with or absorbed as an adult. That's fine too, as your new professional skills will teach you how to express that knowledge in a way that communicates with others who need to know.
Creative people create new intellectual capital. Laws have been set up to protect copyright and other forms of intellectual property because the creators need to be given credit and the right to earn royalties and licensing fees for their efforts.
Academic institutions go a step further. They worry about plagiarism, the taking and reusing of other peoples' words and ideas without acknowledgement or proper referencing.
If you don't acknowledge other peoples' work,
You can still re-use ideas by quoting, paraphrasing and summarising. Doing this demonstrates that you're taking the best that's on offer, but you do need to state your references.
The best academic essays go through a number of stages of preparation:
Essay writing and report writing are very different skills.
Reports are very structured and signpost their different sections with hierarchical headings.They usually end with findings and recommendations.
Essays are more organic and don't usually use headings, but have their own conventions. They often argue a hypothesis, or debate a question.
Essays usually have logical introductory and concluding paragraphs.
In the body of the essay, the author usually steps through a logical series of points. They may wander into discussing the pros and cons of the arguments about each point, and give examples and illustrations, for a paragraph or two.
A good essay compares and contrasts the views of a number of sources. It will always reference these views appropriately by citing the sources. In the Harvard style of referencing, the writer gives a short "in-text citation" consisting of an author's name and date of publication, that acts as a signpost to the complete reference in the bibliography at the end of the essay.