Hello Nginx community. Maybe you guys can help me out?

I recently bought a Dell R710 Server for my home network and have installed ProxMox VE 5.3 as the main OS for VMs. I already have multiple VMs hosted on this server, and eventually moved into a lab environment: a GitLab VM, Discourse Forum VM, etc. I'm quite new to setting up a web environment and have been taking the advice of a friend with experience: he suggested I would need to create an Nginx VM that would route the other VMs through my one public IP Address (a Reverse Proxy). And thus why I'm here ...

I have been following this guide so far.
https://www.cyberciti.biz/faq/install-and-configure-nginx-on-ubuntu-linux-18-04-lts/

I have created an Ubuntu 18.04 LTS VM and from there followed all the steps up to "Test and gracefully reload nginx server". I have set Forwarded port 80 of this VM's local address, and have gotten the "Welcome to nginx!" message when I connect to my External IP with HTTP in a browser.

Now, back to what I was saying before: I have gotten to "Test and gracefully reload nginx server" without any issues and when I run the following command (Let's say my reserved DNS is "nginx.myreserveddns.com"):
# host nginx.myreserveddns.com
nginx.myreserveddns.com has address 92.242.140.22

That is definitely not my IP, and I've read that 92.242.140.22 is the Public IP for BAREFRUIT-ERRORHANDLING (https://ipinfo.io/AS45028/92.242.140.0/24)? When I type in that IP in a browser (92.242.140.22), I get "Sorry, 92.242.140.22 is unavailable or may not existed", but of course this IP probably isn't what I should be trying to connect to I imagine. Anyways when I try connecting to nginx.myreserveddns.com in a browser, I get that "Sorry, ngx.myreserveddns.com is unavailable or may not existed". So clearly its not connecting to the DNS name. Admittedly I have added nginx.myreserveddns.com to the External IP in my DNS list ... however I also have my Proxmox VE reserved for this IP as well. I figured this was causing a conflict, so I disabled it ... but still the same problem for Nginx.

And then I suppose that even if I can get the Nginx VM to connect to the DNS, what needs to be done next? How do I get my other VMs to connect through Nginx? I'm not really sure how Reverse Proxies work, nor how they should be set up to route other servers. The article doesn't explain what to do after Nginx is setup, and just points to the Nginx Wiki.