Peer Reviewed basically means quality control. Peer reviewed articles have been examined by panels of reviewers who are experts in the field. They look for proper use of research methods and the paper's contributions to existing literature. Peer reviewed articles often contain the following (while other articles do not): author credentials and contact information are often listed, the audience is not the general public, tend to include graphs / tables instead of photographys, and include references / citations.
Primary sources provide direct/first hand evidence about an event, person, place, etc. Examples: historical and legal documents, eyewitness accounts, audio/video recording, speeches, and interviews.
Secondary sources describe, discuss, and analyze primary sources. Examples: magazine or newspaper articles, scholarly articles that discuss said person / event.
If you're trying to access the e-books from off campus, use the code: tnws
The above links will direct you to a log on page before you can access the databases. Use your Seattle Public Library card number and pin (usually the last four digits of your phone number) to log in. If you don't have a library card, you can get one here.