Enotes.com has provided users with an extremely easy method of citing various resources. One method is to select "cite" on the page at which you are looking; this is next to the Print and PDF buttons underneath the title. A citation will then pop up for you to copy and paste into your bibliography/Works Cited page.
For instance, the Kite Runner source guide can be cited as follows:
"The Kite Runner: Introduction." Literary Newsmakers for Students. Ed. Marie Rose Napierkowski. Vol. 1. Detroit: Gale, 1998. eNotes.com. January 2006. 25 May 2011.
Of course, when inserting this citation into your bibiliography, be sure to indent every line following the first (hanging indent).
Another option is to utilize Purdue's OWL website (http://owl.english.purdue.edu/) for future questions. It is extremely helpful and comprehensive!