Since you already have a solid idea on how the web works, I’ll skip to the real deal.
First, you need to purchase a domain name. There are thousands of domain websites out there, make sure you choose a highly trusted one.
The next step is to draw an outline of how you want your website to look. Having a sketch will make it easier to build. If you have troubles in laying out a design, hire a UI/UX designer to help you out.
If you want to design your website from scratch without using WordPress, it is still possible. You can get a free template online on how the front-end of your website should look like. For the database design, you can use frameworks for. Django and Laravel are great options.
I personally use the Django framework.
So the choice is yours. I Hope I’m able to your question to your satisfaction.