'Your Mother' provided a pretty good perspective and there's nothing there I'd strongly argue against - I'll add a couple of personal steering suggestions.

• Set up a Github account, learn the basics and share your code. - you'll be surprised by how much help ppl are willing to offer if they can see your code.
• I'd suggest starting with Mojolicious - The included Morbo and Hypnotoad will provide a server and get you coding straight away without worrying too much about web servers and middleware. There are a heap of other reasons including some excellent step-by-step tutorials that will get you up-to-speed quickly. There's some good modern best practice baked in to this path.
• (re)-Learn Javascript and start off your architecture without the thinking of rendering HTML in your backend. I'd suggest picking a modern framework such as VueJS and think of your backend primarily as an API to render in your VueJS application.
• MariaDB and PostgreSQL are great and a relational DB will ultimately serve you well for this type of application but don't be afraid to start out hard coding some JSON structures to start off. A non-relational DB isn't a terrible idea to start ( MongoDB etc ) as it will shift the focus away from perfecting your table structures/schema.