Put quotation marks around any sentences, phrases or distinctive/unusual terms taken word-for-word from the source material.
A direct quotation is usually blended into your own text. You can begin by telling the reader who is speaking, then follow with that person's words. Make sure to clearly mark the boundary between your text and the words you are quoting.
EXAMPLE: Brownlee argues that “captive animals must be allowed to serve as ambassadors for their species”(72).
When quoting more than 3 lines, set the quotation off from the rest of the text in a block quotation, and don’t use quotation marks. The sentence before the quotation should introduce it and the sentence after the quotation should link it to the text that follows. Here's an example of a block quotation, from page 32 of Dorothy Seyler's 1991 book Read, Reason, Write:
Summary and paraphrase are terms often used interchangeably -- that is, as synonyms. They refer, however, to somewhat different activities. A paraphrase, like a summary, is a nonevaluative restatement of someone's writing.... The goal of a paraphrase is to represent accurately, but in simpler words and sentences, the work in question. (32)