In order to avoid plagiarizing and allow your audience to find the original source, you need to use in-text citations in your papers or presentations. Any time you quote, paraphrase or summarize another source, you then must provide a quick reference to that within your paper/presentation.
Let's say we want to cite Tolkien's Lord of the Rings.
Here's what it would look like in a paper:
Tolkien shows the reader Gandalf’s short temper in The Lord of the Rings when the wizard scolds Pippin for dropping a stone in a well; he responds to the accident with “This is a serious journey, not a hobbit walking-party. Throw yourself in next time, and then you will be no further nuisance” (486).
Notice that we told our audience: the author (Tolkien), the source's title (the Lord of the Rings) and the page number where we found the content (486).
Citing The Lord of the Rings in APA style will be pretty similar.
Here's what it would look like in a paper:
Tolkien shows the reader Gandalf’s short temper in The Lord of the Rings when the wizard scolds Pippin for dropping a stone in a well; he replies to the accident saying “This is a serious journey, not a hobbit walking-party. Throw yourself in next time, and then you will be no further nuisance” (p. 486).
APA in-text citations also require author, title of the source and page number, but in APA style we put "p." before the page number.