MLA stands for Modern Languages Association. The MLA Style Manual is often used for formatting and citing references when writing papers in the liberal arts and humanities.
These are sites that will help you "build" citations. They're pretty accurate, but be sure to cover your bases by comparing the citations against those in a style manual. Just choose MLA or APA and the type of source you need to create a citation for (a book, a journal article, etc.), and input all of the necessary information.
Ask a librarian if you need additional assistance.