An income statement shows revenues minus expenses, in order to calculate net income or net loss. Start_ups should project these expected results for the first twelve months of business, then quarterly for the next two years. A list of a company's assets (what you own), liabilities (what you owe), and net worth (assets minus liabilities) is called a balance sheet. The statement of owner's equity shows the owner's initial investment, additional investments, and retained earnings, minus owner withdrawals.
I suggest that you construct easy to read tables and graphs for the financial portion of the plan. The worksheets suggested are: Salaries/Wages and Benefits, Outside Services, Insurance, Advertising Budget, Occupancy Expense, Sales Forecasts, Cost of Projected Product Units, Fixed Assets, Growth (or Start_Up) Expenses, and Miscellaneous Expenses. You may find some of the worksheet templates at PlanWare.org to be useful.
The financial statements section should show the way things are now if you have an existing business, as well as a forward look at your checking account, or projected income statement. The only way a start_up company can provide an income statement and balance sheet is by projecting these figures based upon well defined assumptions. Both start_ups and existing businesses should include a statement of owner's equity.
Do not try to write your business plan in one sitting. As I mentioned in the beginning, for a traditional brick and mortar business, it could take in excess of 100 hours to compile all of the information needed into a comprehensive but yet understandable document. For online businesses, probably not that long. But your final product should be well thought out, well documented and easily understandable.