Parenthetical documentation gives credit to the source—it tells where you found your facts. You MUST put a parenthetical documentation at the END of each sentence that contains facts/ideas from someone else. You put your period after the parenthesis.
You MUST use parenthetical documentation for quotes as well as paraphrased facts.
http://library.austincc.edu/help/mla/ has info on parenthetical and works cited examples. It also shows how to format in a word document.
http://www.easybib.com/help/paren has easy to understand rules for parenthetical documentation.