First question is - are you familiar with Linux command line at all? If not get familiar with it first.

Second you’ll need to own or buy a domain and point it to the server’s IP.

Then install either Ubuntu Server or Debian on the server, setup SSH and run this Ansible project - github.com/LemmyNet/lemmy-ansible

If that’s not comprehensible to you, I’d really recommend getting more familiar with Linux command line and servers before I’d recommend starting a Lemmy instance.