Is there a good guide on how to access services from outside my network?

I have Plex, Radarr, Sonarr, Overseerr etc running in Docker containers, but have never found a good guide on how to access these (safely) from outside. I resort to connecting to a server running VNC. I’ve tried nginx but didn’t understand it, also tried Cloudflare (ditto). Is there a good, easy to understand guide on how to...