Facebook is currently developed to give its people the power to build up their strong community as well as bring the whole world to come closer together. Facebook now contains about over two billion people around the world to help share ideas, provide support, and make everything differences. One of the most important missions of Facebook is to promote economic opportunity, create jobs, and strengthen the economy. There are a lot of reasons why you should use Facebook to promote your online store, including:
Read this article and you'll know how to do marketing for your online business with Facebook: https://avada.io/resources/market-your-business-with-facebook.html
Marketing is a generic term. For eCommerce stores, Marketing usually means driving traffic and increase brand awareness to your store. If that's what you mean, then there are some techniques to market your store:
All of the 4 techniques were described in detail within this article about how to increase your brand awareness.
If you are just starting out, I suggest you focus on 1 thing at a time. Starting with SEO is a good option.