All citation is not created equally - always check your citation content and formatting with your instructor's preferred style manual!
Citation is the act of identifying sources. Any time you use anyone else's thoughts or language in papers, projects, or reports, you must create a citation to credit that person's authorship. When teachers ask you to write in APA Style, they are referring to the editorial style that many of the social and behavioral sciences have adopted to present written material in the field. Here are some websites that show you how to write papers and create citations in APA format:
Purdue University OWL The Online Writing Lab offers guidance for writing college-level papers, as well as citation instructions