Most of the major style guides can be found at Pace University's Campus Libraries. Call numbers and titles can be found here. Ask at the circulation or reference desk if you're having trouble finding them. Note: access may be limited during fall 2020 semester.
It really isn't that complicated. Yes, it's true that there are many different citation styles. However, the point of all of them is to identify a source in a way that will allow readers to find that source. That is the most important thing for you to keep in mind when you cite: Make sure your citation gives the reader the information he or she needs to find the source you used.
The Excelsior Online Writing Lab offers excellent instruction regarding various style guides. In the past, Purdue University's Online Writing Lab (OWL) Guide was very popular and useful. However, due to changes to the structure and content of OWL that resulted from partnership with a for-profit company, I have decided to stop recommending Purdue Owl.