If you are someone who shies away from planning, or you don't like writing or preparing documents, nevertheless you are going to have to force yourself on this occasion. I say that because it is such a key document for the future success of your business, such a tool throughout its development to return and refer to.
A business that makes sense and is going to be sustainable in the future is one that has that clear vision within which all the smaller parts contribute to make it successful.
It could be, for example, the risk of a change in the economic environment - what are your contingency plans for that in terms of dealing with such a situation? There may be many other risks as well specific to your particular sphere of operation, but that ability to plan ahead for all scenarios makes for a robust business plan.
Describe the manufacturing or operating process and associated costs. Contain believable finical projections, with key data explained and documented.