What's the VPS?
The first thing u have to do is install softwares required to run flarum on ur virtual machine.
What u will going to need?
- Apache or Nginx
- PHP 7+
- MySQL database
- Composer
U can also install some 1-click app that have all of this, i recommend a LAMP instalattion, i use LAMP from Bitnami and works like a charm! With LAMP u will have all of the required things for Flarum (Apache, PHP, MYSQL, etc)
Read the documentation on ur host, they can help with this via chat too.
After that, as said by @datitisev , u only need to follow the installation guide.