Opening my own website with my own script

Hello I have recently wanted to make my own website but I wanted to make it on my own and not use tool like wix wordpass ECT. I have a python script that handle all the htpp request and response and it also handle my database I have also wrote all the HTML pages I need and in those pages I make the request to the server (biside the get request that the browser do they do some post request ) The point is I have a working website and a server but now I'm in a new territory and to be honest I have no idea what to do I will like some guidance of what is a DNS And where to buy a domain name what do I do now if I want to store my website but still run my python script as a server side and how to connect my server to my domain Thank to all the helpers