Which style are you meant to be using? APA? Vancouver? Harvard? Something else? Check your subject outline or assignment instructions to find out.
When you know your style - which is just a set of rules about how to lay out your references - have a look at the Referencing Libguide, where the library has developed a comprehensive folio of referencing style guides.
To build your references, you need to answer at least these four questions about the things you read, watched, listened to, or clicked on:
1. Who created the thing?This can be a person's name, like Harry Potter.
It can be a bunch of people, like Harry Potter, Ron Weasley, Hermione Granger, Alicia Spinner, & Parvati Patel.
It could also be an organisation or institution - this is called a "corporate author" - like Gryffindor House, Hogwarts School of Witchcraft and Wizardry
2. When was the reference published and/or updated?Was it published in 2001, and then updated in 2008? Is it frequently updated?
3. What is the title (and subtitle, if applicable) of the reference?Harry Potter and the Prisoner of Azkaban
Hogwarts: A History
4. Where did you get the reference from?Is it a printed book? Use the publication information
A website? Use the URL or web address
An eBook? Use the DOI (digital object identifier) or URL or web address if there isn't a DOI
A PDF from a government department's website? Use the URL or web address
This is not an exhaustive list, but with these 4 bits of information, you should be able to construct a basic reference. You may need to add some more information, depending on the type of references you have, and the style you're using. Journal articles need to include not just the article title, but also the journal title, volume, issue, and page numbers.
For more information about referencing, please check out the library's Referencing Libguide, or the InfoSkills Road Trip. The staff at the InfoHelp Desk are also available to assist.