There are plenty of resources online, but to get started I would go the easy route that I went and use docker.

Look to set up an “arr” stack. Make sure you have it set up gluetun and link to a VPN.

Essentially, you’ll buy a VPN connectio. Ensure this has P2P and Port Forwarding support.

You then set up docker in a way that first connects the vpn. If the vpn doesn’t work then it won’t start the download client like qbittorrent.

If you wait until after work I can share my docker compose file to give you an idea, but honestly if you’re somewhat capable with a keyboard then you can google you’re way to getting set up.

But also look into whether your ISP cares or not. Mine doesn't and I've been seeding for years without any problems without any vpn.

Think about it let like this,

When you open a port on your router you’re allowing inbound connections from the internet to that port via your WAN IP, with a VPN however, that typically does not work since you’re forcing all your traffic through a specific data centre with its own firewall. Most well developed VPN providers will offer Port Forwarding as a feature which usually opens a random port for people to make those inbound connections, you instruct your download client to use the port your VPN provider gives you so that people can leech from you without exposing your WAN IP.

Hope that makes it easier to understand.