Potential market is an estimate of how many people potentially could buy your product.
Be aware that investors tend to want to work with incorporated businesses over sole proprietorships because there is less legal risk for them.
If you don't know what goes into a successful business plan, here are the essential elements of what to include and why. These breakdowns often are presented as a grid, with bullet points in each section breaking down the most relevant information—so you can probably skip writing full paragraphs here.
More research will help you understand where your target market is spending time online, and will guide you in deciding which marketing channels will be the most effective at reaching them. Drilling down to your specific niche will show investors that there are people who want to buy your product.
Market analysis is a key section of your business plan, whether or not you ever intend for anyone else to read it. Know your goals.
For financing, you'll have a better chance of convincing someone to fund your company if there are plenty of details provided. All the papers and document have been signed and submitted, the loan has been approved and any moment from now our account will be credited with the amount.