For papers which are not classified as student papers, go to 18:45 in the video below to include an abstract and running head. The vast majority of student papers do not need these things. Ask your instructor for clarification if you're unsure which one you should use.
KC APA Guide
Here's a link to the KC APA Guide, an abbreviated APA guide written by Dr. McGuire. This short guide may be able to answer some of your questions and get you started with APA basics.
KC Library APA Guides
The KC library web page has collected several useful APA resources you may want to refer to, including help with formatting and tutorials on adding a running head.
APA's Official Websites
If you can't find the answer to your questions using the previous two resources, you may want to try the the APA Style Blog's search function.
The Purdue OWL (Online Writing Lab)
The OWL@Purdue is a wonderful, up-to-date resource, and this List of Nursing Resources on their site includes loads of APA tips and helps for just about any healthcare track.