Please refer to the official documentation, it’s the only thing we can assist you with here.
If you’re planning to install on a server for other users to access this is the installation you would need to follow.
The standard install uses docker and can be completed in less than 30 minutes.
If you’re going to be using Discourse for development purposes, to create plugins, themes or anything else development installs exist for Ubuntu, Windows and macOS
It depends on where and how your website is hosted. If you already have a VPS and can access it via SSH then you may be able to install Discourse there directly.
Some users have had success with Oracle Cloud installing Discourse on the free tier, but the provided server doesn’t meet the minimum requirements for the standard installation.