Your instructor usually determines which style you must use in your papers.
This page links to information on various styles.
Quick Citation Formatting in Databases. Many databases allow you to format citations into various writing styles. When available, look for the wording “cite” or “cite now,” or see if it is an option after clicking on “save, print, email.”
Generally, you will only use one of these style manuals as a guide for how to cite sources and arrange parts of research papers. However, you may find general advice on research in all of these.
MLA Handbook by 
A Manual for Writers of Research Papers, Theses, and Dissertations by 
Publication Manual of the American Psychological Association by 
The Writing Lab at Purdue University does a superb job of helping to guide students in the use of the writing style guides. Be sure and visit their site once you have put your own citations into the proper format to see check your work.