The Purdue OWL is one of the most reliable and comprehensive sites online for help with APA general formatting guidelines, citations, and writing style.
Citation management software is also very helpful for saving and managing all your references, and generating formatted citations in thousands of different styles. I highly recommend choosing a citation management software and getting familiar with it, especially if you plan to continue research and publication after graduation. The library recommends either EndNote or Zotero.
EndNote can be downloaded for free from adam.pace.edu. Once you graduate you will have to buy updates to the software.
Zotero is free and open-source and can be downloaded at zotero.org. Zotero is completely free up to 300 MB of storage.
See the guides below for more information.