Hello Michelle, APA stands for "American psychological association" they have their own recognized writing style. The "official" version is like 2 inches thick and will make you want to take a long walk off a short pier
I used "A writer's reference" by Diana Hacker to learn. It outlines MLA & APA writing styles. It has good concise examples. I'm sure that their is also a plethora of free stuff online.
I would strongly advise you to practice writing and citing APA. Write a paragraph on whatever you please. Cram in citations from books, newspapers, journals, magazines, internet web sites, etc, etc.
When I first had to learn APA I was irritated and overwhelmed. Now that I know it I'm glad I learned it. Good luck! Any more questions just ask, or send me a private message through the forum.