What does it take to publish website?

I learned web development and build a web app. Now, I need the website to be published. The website is coded in PHP (CSS and other crap as well), uses a MySQL database and allows users to upload files. I know I need a domain but what else? how to make the database reachable online? do I have to get something like aws for uploading even though I do not need much storage? After purchasing a domain do I get a server that I can play around with? please take me for the newbie that I am and tell what do I need from a-z...

To keep the question un-opinionated, tell me something broad (for example instead of saying use fcm, tell me to use a cloud messaging service then mention firebase as an example). many thanks