To find cases for this assignment, I recommend searching in LexisNexis, a database provided by the library (links for all databases mentioned are available in the left-hand sidebar). To search for a case in LexisNexis, use the "look up a legal case" search tool on the LexisNexis home page:
If you have a particular case in mind, you can search for it by citation number or by the parties involved. If you don't have a particular case in mind (or don't know its specific information) you can search by keyword instead.
A guide to the common sections in case documents in LexisNexis is available here.