Personnel: The success of any company depends on their ability to recruit, train and retain quality employees. The amount of emphasis in your plan for this section will depend on the number and type of employees required.
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.
If an online business, you need to go into detail how you will attract customers to your website. General statements like "I will use Face Book ads and email marketing" will contribute almost nothing to helping your cause unless you have detailed statistical analysis of tests you have conducted or of another similar business you have been associated with. If you do not have any data upon which you reference your estimates, it could show lack of proper thought to the remainder of your business plan.
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.