Primary source definition for historians
Historians make a distinction between primary and secondary sources. Primary sources "originate in the time period that historians are studying. They vary a great deal. They may include personal memoirs, government documents, transcripts of legal proceedings, oral histories and traditions, archaeological and biological evidence, and visual sources like paintings and photographs" (Storey 2013, 32). I would add to Storey's definition letters (often called correspondence in published collections), films, maps, newspaper and magazine articles published at the time you're studying, personal papers, meeting minutes, even things like theater/dance costumes! Check with your professor to see what you may be able to use as a primary source.
Secondary source definition
A secondary source interprets a primary source. Journal articles and books are common secondary sources. You create a secondary source when you write a paper that analyzes and interprets a primary source.
Storey, William Kelleher. 2013. Writing history: A guide for students. 4th ed. New York: Oxford University Press.
For research papers at this level, you are generally expected to use secondary sources that are scholarly. Here are some resources that will help you to differentiate scholarly articles and books from popular and self-published books.
Your professor may also require that you must use scholarly articles from scholarly history journals only. If this is the case, focus on using the databases America: History & Life, Historical Abstracts, and JSTOR. When you use JSTOR, limit your searching to the category for history journals, but be aware there may still be a few journals from other disciplines in your results. In those cases, it is a good idea to see if the author's departmental affiliation is listed on the article. If you still have any doubt about whether the journal is acceptable, check with your professor.
In EBSCO products, the difference between "Peer review" and "Academic journals" is that peer reviewed results will include book reviews and opinion pieces from the journal while academic journals will not include book reviews and opinion pieces. To eliminate book reviews and opinion pieces from your "Peer review" results simply select "Academic journals" in the limiters on the left side of the page.