Citing online magazine articles is very similar to print, but make sure the entries contain the URL at the end of the citation (or the name of the database if a URL is not relevant). Access dates are not always important in Chicago Style, but if your instructor requests it, it will belong prior to the URL.
Example:
YoungSmith, Barron. "Date Local: The case against long-distance relationships,"Slate, February 4, 2009. http://www.slate.com/id/2202431/.