The 25 questions on the previous page should have given you a basic understanding of the extent of preparations that you will need to go through before initiating your business. A business plan document consists of the written description and the budget. You should write a clear description of your idea making sure that you have addressed all the areas of the questions. The further along you go the more questions will come up which you will need to consider.
It is important to include everything in your business plan document. The budget is best made on an excel sheet. It should be divided into your expenditure and your income. This simply means that you list them in the relevant categories and come up with your total figures.
Having such a document well prepared will convince your future investor as well as your clients of the value of your business.
Good luck!