I think the first thing you need to decide is whether you are going to offer a product or a service. Let's assume you are a very good student, so you could offer a study guide, which is a product, or you could offer tutoring, which is a service. Or perhaps you are very technologically savvy, in which case you could offer a guide to using technology or you could offer your services in teaching those who are not so good with technology, for example, senior citizens who have recently purchased a new computer. (They really need a great deal of help.)
Once you decide what product or service you are going to provide, you will have to consider what your website will look like, how you will promote your business, for example, through Facebook, and how you will provide for your customers' payments. Will you do this on your own, or will you need to hire others to help you? For example, there are people who specialize in website design, and you might need others to help you create your product or provide your service.
There are just as many aspects to e-commerce as there are to any other form of commerce. But deciding on what you will provide is certainly the beginning of the process.