Primary sources are materials that provide direct evidence or firsthand testimony concerning the period or subject under investigation. These raw, uninterpreted materials document the events witnessed firsthand that have been recorded by the creator(s) of the materials. Primary sources allow you to make your own interpretations without having to rely on what other scholars have already written on the topic.
When trying to find primary sources, look in the bibliography of your best research sources. This will show you what primary sources the author used for their research and is a great place for you to start your own research!