The US National Archives & Records Administration has a wonderful set of tools for (learning to) work with primary source documents.
At https://www.archives.gov/education/teaching-with-documents, you’ll find both handy (printable!) worksheets to guide analysis of primary sources, and a link to their fantastic DocsTeach website, which has both a huge collection of digitized primary sources and teacher/professor-generated activities to use those resources.
Check them out!