How do you reference a web page that lists no author?

When there is no author for a web page, the title moves to the first position of the reference entry:

Example:
All 33 Chile miners freed in flawless rescue. (2010, October 13). Retrieved from http://www.msnbc.msn.com/id/39625809/ns/world_news-americas/

Cite in text the first few words of the reference list entry (usually the title) and the year. Use double quotation marks around the title or abbreviated title.: ("All 33 Chile Miners," 2001).

Note: Use the full title of the web page if it is short for the parenthetical citation. Articles found on the web, like the example above, are not italicized in the reference entry and are not italicized but enclosed in quotations in the in-text citation, just like a newspaper or magazine article. Reports found on the web would be italicized in the reference list, as in Publication Manual (6th ed.) Examples 31, 32, and 33 on pp. 205–206. They would also be italicized in the in-text citation, just like a book.

These posts on the APA Style blog will also be helpful: