Purdue University has an Online APA Style Guide that is extremely helpful and easy to use, organized by the type of citation (in content versus reference section) and then is also divided into authors (single vs. multiple), books versus periodicals versus online citations, conference papers, etc. I strongly encourage you to use this online guide as you prepare your project's references section.
Two of the most common citations you'll make in your reference sections are for journal articles, and for articles retrieved/found online. Here are the models for these two common sources:
Journal article, APA style:
Author, A. A., Author, B. B., & Author, C. C. (Year). Title of article. Title of Periodical, volume number(issue number), pages.
Article retrieved online, APA style:
Author, A. A., & Author, B. B. (Date of publication). Title of article. Title of Online Periodical, volume number(issue number if available). Retrieved from http://www.someaddress.com/full/url/
Bernstein, M. (2002). 10 tips on writing the living Web. A list apart: For people who make websites, 149. Retrieved from http://www.alistapart.com/articles/writeliving