A primary source can be almost anything: an archival object; a painting; a sculpture; a movie; a graphic novel, poem, short story, or other text; a newspaper article; etc.
Spend some time simply brainstorming ideas, and make a short list of potential ideas. You might even make a mind map like this example on the right.
Cover art of post-apocalyptic novel Oryx and Crake by Margaret Atwood (2003)
Find several things that interest you. They could be films, images, books, items, etc. You can do simple Google searches around topics for more ideas of actual primary source items also.
Check UC Library Search to see if the library has a free copy of this primary source (esp. books and films).
Look in Humanities Core Research Guide: Primary Sources. This guide has multiple links to databases, digital libraries, and other places to find online or digitized primary sources. You can find sources by format (e.g. film, images, digitized texts) and also some sources by theme.
Make an appointment with a librarian for more ideas if you are stuck
TIP: You should find more than one item you're interested in writing about.
TIP: Do not get too attached to any one idea or object at this stage.