How To Sett Up Your Online Shop
There are a lot of options out there for selling online from shopify, Amazon or ebay to hosting your own site and using woocommerce. Woocommerce in my opinion is one of the best options out there and its free. You can add a ton of extensions that will enhance your users shopping experience from follow up emails to abondoned cart reminders, subscription and mebership options to name but a few.
Before you so any of that you have to research your intended market, find a product you can stand behind and create a plan. You will have to consider logistics, stocking the product or not. You may want to try drop shipping, selling a digital product or subscription.
What ever your choice is make sure you are a domain expert for that product or service. Once you have set up your shopping cart you can then start marketing via long form blog posts, guest posts or paid advertising.
Best of luck!