Download a couple of free nifty little "down and dirty" handouts that summarize important elements of APA style: APA Quick Guide, APA Electronic Reference Guide, and Recognizing Scholarly Publications.
 
Also, try out http://citationmachine.net/. This free site lets you type in information about your reference (title, author, date of publication, and so forth), and then it gives you the correctly cited reference for your APA-style reference list and also for your in-text citation. All you do is cut and paste, being sure to format your reference list with double spacing and hanging indent, of course (more on that later). It's quite spiffy and super-easy to use. It does MLA style, too, if that's what you need.