Style guides describe how to properly and consistently cite your sources of information. They provide guidance on the appropriate way to include information such as the author, title and publisher of a book or the volume, issue, and page numbers of a journal article. Talk to your professor about which citation style they want you to use.
A Pocket Style Manual with Exercises by 
Zotero is a free, open source browser app that collects, manages, cites, and shares your research sources. There is a browser extension that saves info and connects with the desktop Zotero (you need both desktop and browser extension).
For Zotero help, contact:
Bill Kelm, bkelm@willamette.edu or
John Repplinger, jrepplin@willamette.edu