Connect to your VPS SSH interface using credentials provided by your hosting provider. Upon entering your server credential into your SSH client you can start installation of Backend side.
Deployment of server side is based on Docker. Using Docker helps with easier installation, less chance of OS configuration affecting application, easier updates to newer version and many other benefits that Continues Deployment offers.
Some hosting provide VPS with Docker preinstalled. For example DigitalOcean Droplets. Install Docker step can be skipped if you get your hosting with docker preinstalled.
In order to install Docker & Docker Compose you can rely on documentation Docker provides based on your server's OS & Distro: