You may receive additional answers to this question as we all have experienced different ways of citing online sources in various works. As an instructor I would recommend that you follow the APA guideline for citing
Non-Periodicals , Non Periodical Report, or Non-Periodical Web Document
Get all the information that you can, for example, Enotes.com, the name of the educator/teacher/user who provided the answer, the topic, the weblink, and the date when it was retrieved. For example, your bibliography or reference section would read:
Baxter, A. (2014, February 20) Literature forum. Retrieved from http://www.enotes.com/homework-help/use-content-find-e-notes-how-do-reference-work-474705 on February 20, 2014
If no date is available for when the educator posted the answer, write (n.d) or no date in the parenthesis. This format is the one that is recommended for people who get information from YouTube channels, by the way.
Also, you do not need to write "Literature forum" you can just keep it as "Literature" as that is the category from where you retrieved the answer. The important thing is to give as much information as possible so that if you are ever fact-checked the source can be found exactly as you posted it. Last names and year are used for in-text citations (Baxter, 2014).
I am including two awesome resources for the future and in case you want to explore other sources that you can cite from.
Also, check out the Essay Lab at Enotes.There are a lot of other resources there that you will find useful.