For your papers, you are being asked to use a citation style that's likely different from what you've used before.
Your in-text citations should be placed at the end of the sentence, and should simply be a number (or numbers, if citing more than one source). The numbers should refer readers to your reference list at the end of your paper, which should be sorted numerically based on the order in which they are cited in the body of the paper (NOT alphabetically).
The sources in your reference list may vary a little in format, depending on the type of resource you're citing (journal article, website, etc.), but should include at least the following information: author(s); title of resource; journal or website title; date of publication; volume, issue, and page numbers, doi or other direct url.
Use the pages linked below for additional guidelines and examples. You can also take a look at this paper for a real-world example:
Ingram D, Crook T. Rise in babesiosis cases, Pennsylvania, USA, 2005–2018. Emerg Infect Dis. 2020;26(8):1703-1709. https://dx.doi.org/10.3201/eid2608.191293
Again, don't hesitate to ask if you're unsure about your references!
Citation managers are extremely useful tools created to help researchers keep track of all their sources. I highly recommend checking them out as an option, either for this class or another. If you have any questions about them, please don't hesitate to ask.