What programs give you: your own domain, the ability to update frequently, & the ability to apply promo codes/discounts whenever you want?
Sounds like you don't know much about web development.
You should probably go with a hosted e-commerce solution like Shopify.
Sure, they charge a bit more per month but they'll take care of figuring out the complicated parts for you.
These requirements are available at almost every website hosting service.
you need to know how to set up a web site and manage it, meaning you have to design it, get it registered and able to manage it, change it, add to it, etc
you need to learn how to make a web site
My cousin uses godaddy.