This excellent online guide to MLA style covers most of the situations you're likely to encounter. Note that its table of contents is at the bottom of each page, not on the side.
The Citing sources page on Rohrbach Library’s site (linked beneath the Find Information header on the home page) points toward many tools to help with several citation styles as well as labor-saving bibliographic managers.
Rohrbach Library keeps several copies of the most recent MLA style manual.
Get in the habit of collecting information about your sources as you use them. The library's article databases will invariably supply what you need for your citations, and many of the databases have facilities for formatting and saving citations as well.
Citing your sources is an essential part of your work as a member of a scholarly community. Whenever you're unsure about the protocol and can't find a satisfactory answer on your own, ask!