Q. How do I make an MLA citation for an individual, unauthored essay within an anthology?

You can view the rules for citing this type of resource in Purdue OWL, linked below.  Scroll down to the section titled A Work in an Anthology, Reference, or Collection.  Here is the basic format for such citations:

Lastname, First name. "Title of Essay." Title of Collection, edited by Editor's Name(s), Publisher, Year, page range of entry. 

If there is no author listed for the essay, follow the formatting above but start at "Title of Essay".  Still list the editor(s) of the larger anthology.