Primary sources are the thing that you're studying, or firsthand evidence regarding the thing that you're studying.
Here's an example. If you're studying Fanon's The Wretched of the Earth, then your primary sources might be...
Here's another example. If you're preparing for a debate about whether some books should be banned, then your primary sources might be...
Some primary sources can be found in Simpson Library's collection or databases. Many primary sources can be found online for free. For help finding primary sources, ask a librarian.