These citations appear in parentheses and usually consist of the author(s) last name(s), year the information was published, and page number(s) of the source you are citing. The sentence punctuation goes outside the parentheses.
Example - one author:
Louv (2012) states that the lack of outside activity is a “Nature Deficit Disorder” (p. 34).
Example - two authors:
“Teachers who provide nature play set the stage for lifelong approaches to learning” (Talbot & Frost, 2014, p. 21).
Web sources may not have a page number, so you won't include a page number in your in-text citation.