Contemporary translations of Greek and Roman plays are available in Holman Library. Search or browse the catalog or go directly to Holman Library ebook collections.
Ebsco eBooks (linked right) has a collection of classic plays.
"Roman Theatre." Image from original photograph by elbisreverri; some rights reserved under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 licence.
Search by specific title or enter "Greek plays" or "Classical plays" to find titles.
Here are a few 'classics' to get you started:
Search for print books, ebooks, and videos available at the library and online.
Use filters on the left to limit by specific source type, date range, and more.
The next step in the process is to find evidence to support your own argument. Books are a great place to browse for more evidence. Holman Library has a collection of over 25,000 electronic books that you can read online.