There are 2 ways to reference in-text: Paraphrasing or direct quotes.
Don't overuse direct quotes in your assignments but if you do want to use them remember you need to use quotation marks and include the author, date and page number (paragraph number if no page number is available).
For example: According to Esterhuizen (2019, p.10) "Individuals are unique, and human factors may be uncertain, even messy."
"the best way is to establish a routine and stick to it Monday to Friday" (Prospects, 2020, para.16).
Esterhuizen, P. (2019). Reflective practice in nursing (4th ed.). Learning Matters.
Prospects. (2020). 5 tips for studying at home. https://www.nus.org.uk/en/advice/your-study/5-tips-for-studying-at-home