Citing web pages correctly is quite easy. You may have to search for some information on other parts of a site than the page you're looking at.
According to guidelines in the MLA Handbook for Writers of Research Papers (1999), a bibliographic citation follows this order, using the punctuation shown in each section:
Author surname, Author firstname. List entries alphabetically by author (if no author list title first)
Title (2a, "Title of Page." 2b, Title of Site).
Date page was published or last updated.
Name of institution associated with the site.
Date you accessed the site.
The URL of the site.
Separate entries with periods.
So, if you accessed the Incredible Art Department's Website on July 4, 2013, and it had last been updated on December 1, 2012, your citation would look like this:
Rohrer, Ken. Incredible Art Department website. 1 Dec. 2012.
Incredible Art Department. 4 July 2013.
If you want to credit a particular page of the site, you do so like this:
Rohrer, Ken. <"Title of Page."> Incredible Art Department Website. 1 Dec. 2012. Incredible Art Department.
4 July 2013.
<URL of Page, including the http://>
How do I determine the last date the page was updated? Simply go to this URL and do a search on the URL of the page you're looking for and look at the date. For example, let's say the URL you want to cite is located on https://www.incredibleart.org/aeai/aeai.html. You simply copy this URL and when you get to the site map page, you do a "find" or "Search" on the page using the copied URL. It will go to the URL you're looking for and this is the date the page was loast modified: <lastmod>2013-06-10</lastmod>