Primary sources require a little more analysis than secondary sources, but if you put in the work you'll arrive at a fresh perspective on past events. No one will interpret a source in exactly same way and there isn't one right way, but primary source can be misleading if you don't read them closely and think about the context in which they were created. Here are some questions to get you started in interpreting a primary source.
The physical nature of the source
What can you learn from the form of the source? For example, was it written on fancy paper in elegant handwriting, or on scrap-paper, scribbled in pencil?
Has anyone added annotations to it? Other signs of how it was used?
The creator or author
Who created this document?
Why did they create it? Was there a point they were trying to get across?
Is the message explicit, or are there implicit messages as well?
What do you know about the author? Race, sex, class, occupation, religion, age, region, political beliefs?
Who was the intended audience for this document?
Was it meant for one person specifically, or for the public?
How would the audience have encountered this source?
How does the language work? What can the author’s choice of words tell you?
Can the document be taken literally?
What about the silences? Are there things the author chose not to include?
The historical context
What else was happening at the time this document was created?
Is the author responding to something? Are they in dialogue with others?
What does the document tell you about the time and place in which it was produced?