You've already set up your library and have acquainted yourself with adding resources and copies. Here are links to articles that walk you through day-to-day use of Populi Library.
Catalog is where you create, organize, and search for resources and copies.
Read about the library catalog...
Links take you to an external website. They are accessible to all your patrons and visitors. They provide a way to create a useful resource for your school—for example, a list of links to other local schools with public libraries or other educational institutions.
Read about library links...
A patron is anyone who can check out a resource copy from your library. Patrons can take resources on loan, place holds, leave recommendations and reviews, and be charged fines. All of this information (as well as contact info) can be found on a patron's library profile (you have a profile, too).
Read about patrons and library profiles...
The Circulation view features a number of circulation-related reports (active loans, transits, etc.). The term "circulation" also refers to tasks like managing the pull list and checking resources in and out for patrons.