Start by writing a description of your business, including what stage of development it is currently in (conception, start_up, first year, mature, exit) and your plans for growth. Discuss the nature of your business, the main products and services you offer, the market for your products and services, and how and by whom the business is operated.
Summary Section: This section is where you will be able to attach or explain any detail not applicable to the previous sections. This section should be used to provide the financial statements of the Principle's involved in the business and any other data you think an investor would be interested in seeing.
Describe your most important company strengths and core competencies. What factors will make the company succeed? What do you think your major competitive strengths will be? What background, experience, skills, and strengths do you personally bring to this new venture?
So, although a detailed business plan may not be required for an online business, I am going to include it here so you can at least look at and consider each section and determine yourself if it applies to your business.