You may already have some background in your course topic, but more than likely this is your first in-depth encounter with the issues you are going to write about. In most cases, your course text--Medieval Pets--and your writing professor will provide you with a basic grasp of one or more problems related to the course topics and readings.
You may also find problems identified in individual chapters of the course text, or in the works it cites in its footnotes and bibliography. Perhaps more compelling and to the point, you should try to identify an organization or constituency that would be interested in having someone research this problem for them.
Understanding the rhetorical situation--who are your readers, why will they find this white paper valuable? What do they need to know? How will they use what you are going to provide to them? What’s their stake in this problem?
Find out whether those who are affected regard it as a problem
Before you go further, you need to establish that those who seem to be affected by this problem actually regard it as a problem. You have an ethical responsibility not to come from outside of a discourse community or neighborhood and, from some presumed position of privilege, declare a problem when those affected do not see it as one. For example, an uninformed, well-meaning person might decide that an apparently weedy, untended field in another part of the city must be mowed, when in fact this this seemingly unkempt field is an expertly planned and tended native pollinator meadow, providing habitat for endangered urban wildlife.
Since white papers are commonly focused on current problems of public interest, an ethical author/researcher must therefore search public sources to see how the problem is defined and viewed by those whom it directly affects. This is the first stage of your research and will help you orient yourself and narrow your focus. Sources may include social media, newspapers, interviews, local organizations, and websites. As you search, make sure to take notes and document what you learn about how people are defining the problem, who the stakeholders are (who is being impacted by the problem), and what kinds of disagreements are expressed over whether it’s a problem, how to define the problem, what is seen as the history and significance of the problem, and how, if any, solutions have been tried and their results.