There are two parts to every APA citation:
In general, these consist of the last name of the author(s) followed by the publication date, and can be expressed as parenthetical or narrative citations. See the In-Text Citations page for further explanation and formatting information.
Reference List Entries
In general, a reference is made up of four elements: author, date, title and source. These elements provide the information required to identify and retrieve the works cited in the text.
The rest of this guide contains information on how to format reference list entries for a variety of sources.
Putting it Together
Check out the Purdue OWL site to see a sample paper written in APA citation style.