Can someone please clearly explain what an in-text MLA citation is?

n MLA style, referring to the works of others in your text is done by using what's known as parenthetical citation. Immediately following a quotation from a source or a paraphrase of a source's ideas, you place the authors name followed by a space and the relevant page number(s).

Human beings have been described as "symbol-using animals" (Burke 3).

When a source has no known author, use a shortened title of the work instead of an author name. Place the title in quotation marks if it's a short work, or italicize or underline it if it's a longer work.

Your in-text citation will correspond with an entry in your Works Cited page, which, for the Burke citation above, will look something like this:

Burke, Kenneth. Language as Symbolic Action: Essays on Life, Literature, and Method. Berkeley: U of California P, 1966.

Bobpursley is exactly right. And if you need to see specifics regarding all different types of resources and how to cite them, here is a really good website:
http://wwwold.ccc.commnet.edu/mla/
Hold your cursor over the words CITING SOURCES and choose from the secondary menu that shows up: books, newspaper or magazine articles, Internet sites, etc.

=)