Use the HELP in Microsoft Word and type in MLA Format to see a list of guides and web pages that can help.
There are also a number of tutorials on YouTube.
The source for this information is the Online Writing Lab (OWL) at Purdue University. The easiest way to get there is to Google: Purdue Owl MLA.
MLA format for Magazine Articles:
Author's last name, Author's first name. "Title of Article: Subtitle." Title of Periodical or Magazine Day Month Year: pages. Medium of Publication.
Here's an example:
Slouka, Mark. "Dehumanized: When Math and Science Rule the School." Harper's Magazine Sep. 2009: 38-40. Web. 17 Oct. 2013.