You are to defend to your CEO, in a written proposal (memo format), why a risk management department is necessary to your organization. This paper presumes you do not have a risk management function and you are defending the need to establish such a function. In other words, take the approach you do not have a risk function.
(If you do not work pick a prior business. If you have never worked, pick a current organization.) Please keep in mind CEOs understand money and return on investment. At beginning, provide a basis statement of the responsibility for your organization: short paragraph explaining the job/mission of your organization.