Your Works Cited page is made up of citations of all of the sources that you used. The Works Cited is important in order to avoid plagiarism!
Your sources should be listed in alphabetical order.
When you are looking for information from a source in order to create an MLA citation, you need to look for the following information. (Note: You probably won't find ALL of these things! It depends on the type of source.)
MLA Formatting Quick Reference Guide
Purdue OWL (a great place to look up how to cite specific types of sources!)
Formatting In-Text Citations