Organization and content of the business plan will evolve as it is prepared. For example, if the driving force of the plan is marketing or sales then a preponderance of the analysis and plan_of_action section will be more up_front and sales oriented in tone. With business plan's the world is your oyster; think from the center out to the edges and think outside of the box.
For an online business, a detailed and in depth business plan is usually not necessary unless you are trying to combine your online business with a traditional business. For most online business startups, the detail involved with planning a traditional business is not required. However, it would still be beneficial to you if most of the topics were still covered, even if only briefly. Having a written plan in front of you will help you to focus on important aspects of the business.