What goods and or services will you be selling? These are your outputs. It is important to be as clear and as detailed as possible about this. They could be, for example, tangible products, specialist services, or, for knowledge-based enterprises, education or consultancy.
What do you need to buy in order to produce your outputs? These are your inputs. Again, they could be tangible goods or less tangible things like expertise or data. They may include training.
What are the processes by which the inputs become outputs? This is, if you like, the machinery of the business and is at the very heart of the enterprise, so you need to clearly describe these processes in some detail.
Your business may or may not be set up to make a profit for its members. Even if it is not for personal profit, it must nevertheless make a surplus or it will not be sustainable. If it relies on a constant stream of donated time or money, these count as inputs (although this model is not recommended as it has an obvious critical dependency).
Therefore the outputs must generate more money than the cost of the inputs. This in turn means that the business activity must add value to the inputs. You should be able to say how your business creates value in this way, how it makes something that wasn't there before, that your customers will pay so much for that it more than covers the cost of your inputs.
You should also be able to say why you think your enterprise will be able to generate value for the foreseeable future. How will you develop your products? How will you assure quality?