Tired of working for other companies and thinking of starting an online Retro Game business. Where do I even start?

Hi, guys, need some advice from people with experience on building a business from ground up.I decided that Im tired of working my ass off for other companies and getting a mediocre payment for it, people say that to be an entrepreneur is not easy and you have to work really hard to make it happen but Im already working really hard, but for others, not myself.Since I remember, I always wanted to have my own business, be my own boss and build something of my own, but I never had a great idea to create one and never had the courage to put some ideas do practice.I graduated in advertising and I have lots of experience in Design and Social Media so I think that would be a good idea to start an online business, start an E-commerce or something like that.I've always been passionate about video games, retro games to be more specific, so I thought on create an online store to sell retro games related stuff like the games themselves, shirts, some retro game decoration. As it turns out, its really hard to find these kind of things in my country and I think would be really awesome if there was a store specialized on that.TBH, I imagine that I would not make a huge bank out of it, but the idea is just to start something simple and easy to get some experience out of it and perhaps start other more lucrative businesses in the future.But im not even sure how I would get inventory for it, would I go to local stores and resell it online? if so, how would I make a profit out of it and stay competitive in the market? What are other things that I need to worry about before even starting it?Any tips that you can provide would be really helpful. see hubwealthy.com/wealthy