You may not need to be an expert in Double-Entry accounting, but the person who is responsible for creating the financial statements better get pretty good at it. If that is you, go back through the book and focus on the ‘gray’ sheets. Study the examples and see how the Double-Entry method acts as a check and balance of your books.
The Business plan is a written document that clearly and convincingly demonstrates that your business can sell enough of it products and services to make a satisfactory profit for yourself; provide sufficient profit to attract lenders and potential investors and finally to provide sufficient cash flow to service debt and pay investors. That is what business is all about.