The Citing sources page on Rohrbach Library’s site (linked beneath Research Tools at the top of every page) points toward many tools to help with several citation styles as well as labor-saving bibliographic managers.
The Online Writing Lab (OWL) at Purdue University does an excellent job of describing and demonstrating APA format here. (Look for Reference List - Electronic Sources in the left menu for help citing articles from online databases.)
APA published their own online guide to APA style here.
These books are available in the library's reference collection:
Publication Manual of the American Psychological Association, Sixth Edition
Ref BF 76.7
Here is an image of an APA format title page, from OWL: