A primary source is a document or piece of evidence written or created during the time period you are studying. A primary source allows you to examine evidence firsthand without being affected by other opinions.
Finding primary sources for this time period can be a more a more difficult task than finding primary sources for more modern history where photography, diaries, and videos are available.
Keep in mind you may be able to utilize the primary sources found in some of your secondary sources. For example, you might find a map in a book from the time period you are studying or find an image of hieroglyphics you want to utilize. While the book would be a secondary source, those parts could count as primary sources.
If you have questions about this or need clarification, ask a librarian or your instructor.