The databases you'll use to find articles have a button that will generate a reference for you, but you should still check to make sure it was generated correctly. You can also use Zotero Bib (linked below) to generate a reference. Again, check to make sure it's correct. Use the list of APA Style Reference Examples (linked below) to get familiar with formatting the most common types of references.
It's important to cite sources you used in your research for several reasons:
You must cite:
When in doubt, be safe and cite your source!