A popular option for citation management is Mendeley, a free program that organizes both your references and your PDFs, with some social media capabilities.
Among other features, Mendeley has a plug-in for inserting citations into your papers, will create formatted bibliographies, and allows you to annotate and share your PDFs. It will sync all of your citations and annotated PDFs across the web and your devices. It even has a mobile app for PDF reading and annotation.
The Mendeley Resource Center has help guides and video tutorials.
For in-person assistance, please request an appointment with a librarian.