Create a proposal project, which is addressing a problem in your organization or community.
You will need to do an industry research to justify your proposal.
Some hints to support your solution with financial formulas - ROI, NPV etc you find might be based on existing data and/or benchmarks from other similar projects.
If your proposal is a new creative solution, which has never been done before base your predictions on projections in the industry.
1. Describe the organization you are proposing the project to - create the business case and outline the problem you will address in your proposal.
2. Justification analysis of the proposed budget, scope, time of the project.
3. Outline the solution you are proposing to solve the business problem.
4. Create project schedule and WBS in MS Project, and assign resources to your project. This could be a high level as you may not have all details.
Be creative, there is no limit of budget, industry or geography for this proposal.