The Modern Language Association (MLA) maintains a helpful free website on how to use MLA citation style. For example, the link above leads to the Citations by Format guide that provides sample citations for physical books as well as electronic resources (books, journals, videos, and more).
Purdue University, MLA Formatting and Style Guide
This free resource, part of Purdue University's Online Writing Lab or OWL, offers examples on how to write citations in MLA style. Ignore the interactive ads and use the menu on the left side of the webpage to navigate the contents of the site (for example, click the link for MLA Sample Paper to go directly to that section).