Here are some links that will help you with MLA Style. Diana Hacker has published a number of great guides related to writing essays and documenting sources etc. It appears that her entire book is not online. Check out this section of her website for information on using MLA style

http://www.dianahacker.com/resdoc/humanities/list.html

This page at her site shows how to do "in-text citations"

http://www.dianahacker.com/resdoc/humanities/intext.html

There are many other sources online for similar information, though they are not as comprehensive as Hacker's site.

Here are a few others that might be of help:
http://owl.english.purdue.edu/handouts/research/r_mla.html
http://www.wisc.edu/writing/Handbook/DocMLA.html
http://www.english.uiuc.edu/cws/wworkshop/MLA/bibliographymla.htm

This site deals with how to cite online sources of information.
http://www.westwords.com/guffey/mla.html

These should answer all your questions. If you're an English major though, or still plan on taking English courses, purchasing the MLA Style Guide is a good investment.
You can purchase it online at http://www.mla.org/bookstore: