The Purdue Online Writing Lab (Purdue OWL) is a thorough online resource covering many different citation styles, including APA. It includes help on:
The Student Center for Academic Achievement (SCAA) at CSU East Bay provides many services to help you with your writing, including:
Citation software helps you to:
CSUEB provides free access to EndNote Web (available through the Web of Science database). Additionally, Zotero and Medeley are available for free online. For detailed comparisons between these three see Wikipedia's Comparison of reference management software page.