When you look at or do something, you develop a perspective. You have a different position or view of something. So, the phrase to "to walk a mile in another person's shoes" is appropriate to illustrate the concept of perspective. This means abandoning your own thoughts and ways of doing things from the perspective of another person.
When looking at primary source material in history it is often from the first person perspective. This means the person in question is experiencing the event firsthand. These sources are found in diaries, manuscripts, and oral histories. This is where the topic of the fur trade comes in.
Also, as a refresher, here is a link to a video on primary and secondary sources. This task is to be done alone, no groups.