Unfortunately, I can't give you access to the MLA Handbook on line, but I have copied the introduction of Section 5.6 for your edification:

5.6.1. Introduction: In performing research on the World Wide Web, you may access bibliographic databases, academic journals, archives of print publications, critical editions, reference works, dissertations, and a wide variety of other documents and recordings. Citations of Web publications share some traits with those of print publications and other traits with those of reprinted works, broadcasts, and live performances. For example, most works on the Web have an author, a title, and publication information and are thus analogous to print publications. But while readers seeking a cited print publication can be reasonably assured that a copy in a local library will be identical to that consulted by the author, they can be less certain that a Web publication will be so. Electronic texts can be updated easily and at irregular intervals. They may also be distributed in multiple databases and accessed through a variety of interfaces displayed on different kinds of equipment. Multiple versions of any work may be available. In this sense, then, accessing a source on the Web is akin to commissioning a performance. Any version of a Web source is potentially different from any past or future version and must be considered unique. Scholars therefore need to record the date of access as well as the publication data when citing sources on the Web.

Publications on the Web present special challenges for documentation. Because of the fluidity of the network and the many hypertextual links between works accessed there, it is often difficult to determine where one work stops and another begins. How, for example, does one define a Web site? One definition would consider all pages affiliated with a particular domain name, like www.mla.org, to constitute a site. Another view would consider all the pages organized by a particular editor or project team as a site, even if the project is housed under a larger body’s domain name or distributed over several domains; the Victorian Women Writers Project, for example, appears under Indiana University’s domain name (www.indiana.edu). Since both views have merit, the guidelines presented here do not take one side but instead offer a method to record the relation of works on the Web to the information hierarchies surrounding them.

In the past, this handbook recommended including URLs of Web sources in works-cited-list entries. Inclusion of URLs has proved to have limited value, however, for they often change, can be specific to a subscriber or a session of use, and can be so long and complex that typing them into a browser is cumbersome and prone to transcription errors. Readers are now more likely to find resources on the Web by searching for titles and authors’ names than by typing URLs. You should include a URL as supplementary information only when the reader probably cannot locate the source without it or when your instructor requires it. If you present a URL, give it immediately following the date of access, a period, and a space. Enclose the URL in angle brackets, and conclude with a period. If a URL must be divided between two lines, break it only after the double slashes or a single slash; do not introduce a hyphen at the break or allow your word-processing program to do so. If possible, give the complete address, including http, for the specific work you are citing (see fig. 29).

The recommendations in this section mostly treat peer-reviewed, scholarly sources and primary sources for which a considerable amount of relevant publication information is available. In truth, though, many sources do not supply all desired information—for instance, many texts do not include reference markers, such as page or paragraph numbers, so it is difficult if not impossible to direct a reader to the exact location of the material you are citing. Thus, while aiming for comprehensiveness, writers must often settle for citing whatever information is available to them. Since the Web can deliver sound and images as well as written text, you may want to describe your source in your text or endnotes when there is a risk that readers will not appreciate important aspects of the work. MLA style is flexible, and sometimes you must improvise to record features not anticipated by this handbook. In some cases, citation formats devised to handle complex print publications may serve as a basis for improvisation; see in particular the sections on an article in a reference book (5.5.7), scholarly editions (5.5.10), translations (5.5.11), and government publications (5.5.20). Remember to be consistent in your formatting throughout your work. Since sites and other resources on the Web sometimes disappear altogether, you should consider downloading or printing the material you use during your research, so that you can verify it if it is inaccessible later.