Author. "Title of Article". Name of Site. Organization / Sponsor of the site (if not named as the author or name of site). Date Accessed. Web Address. If you can't find all of the information above, cite what is available.
Examples of on-line reference sites:
Encyclopedic Sites AboutWikipediaHow Stuff Works
Dictionaries and Thesauri BartlebyMerriam-Webster On-LineRhymezone