In most college libraries we use the Library of Congress classification system to organize materials. Books are shelved next to other items on related topics and organized by call numbers (the address of each book).
Start with looking for the first letters. These will be alphabetical on the shelf: P, PN, PR. Each floor of Doheny Library houses a different set of call numbers. The maps near the elevator will tell you which floor belongs to which number.
Within each letter, items will be in order according to the subject number, from lowest to highest. For example, a call number that begins PN 3433.6 will precede a call number that begins PN 3500.5.
From then on, items will be organized alphabetically and sorted as if a decimal point precedes them. So PN 100 .B1 precedes PN 100 .B175, followed by PN 100 .B2.