Use this guide as a map to researching your topic in Ancient Greece, starting with the basic resources, L'Annee Philologique, Brill's New Pauly, Cambridge Companions Online, Cambridge Histories Online, Oxford Bibliographies Online: Classics, JSTOR and TOCS-IN.
Use the Resources by Topic page to delve more deeply in subject specific resources like Epigraphy or Numismatics.
For a basic overview of ancient Greece, be sure to look at Brill's New Pauly. See also the British Museum's Ancient Greece and the Metropolitan Museum of Art's Greek and Roman Art site. Other online guides include the PBS guide to The Greeks; The Acropolis Museum; and Odysseus. For an excellent print resource see the Encyclopedia of Ancient Greece, in the reference departments in both Lilly and Perkins Libraries, call number: Ref DF16 .S23 2005. Another important print resource is Wiley's Encyclopedia of the Ancient World in the Perkins Library, call number: Ref D54 .E53 2013.
To cite sources correctly, go to that page for examples of different citation styles. (Though you may want to investigate some of the bibliographic managers Duke has available which will import your references and automatically format the bibliography).
If you need assistance, please don't hesitate to contact me. We may be able to solve a problem via email, or we can set up a research appointment where we walk through the steps of finding sources together.
Good luck with your explorations of Ancient Greece!