Assistance Setting Up First Containers

My background: Mostly focused on routing and switching, TCP/IP, large enterprise networks, ISP backbones/fiber, etc. Long history of basic Linux administration. Familiar with a wide variety of tech. About 20 years of experience working for various organizations such as Xerox, AT&T, Verizon, etc.

I'm at my wits end here. This is a personal project I'm doing to try and learn containers and new advancements in the tech industry. Also slowly working towards the RHCSA. I've been reading into docker (and podman for RHEL/SUSE). I have no issues with legacy virtual machines and I learned those concepts quickly. I've been trying for a few weeks now to really understand how to stand up a functioning set of docker containers. I've ran through dozens of examples but they just don't really fit anything together and tend to focus on one aspect. Here is basically what I'm trying to do:

| RHEL 8.5 Minimal Server (firewall-cmd commands to protect host and containers)
|- Redhat UBI8 with NGINX Reverse Proxy Container
|- - Redhat UBI8 with .NET Core for ASP website
|- - Redhat UBI8 with Apache and PHP
|- - - Redhat UBI8 with Back end database, MariaDB
|- - - Oracle Linux with Oracle Express DB

Can someone help me through what needs to be done to complete even the first part of this? I have the RHEL 8.5 server up and running with podman. I've downloaded the UBI8 containers and some other containers locally. What is the proper way to configure the first container with NGINX, and then permanently run it as a service, while properly pointing to, lets say, a second container with Apache and PHP running, which is also launched automatically as a service?

Let's start here, lets just use a nginx webs server to begin. I've pulled:
registry.access.redhat.com/ubi8/nginx-120
registry.access.redhat.com/ubi8/php-74

What do I need to do to run these both as a service to launch automatically, to configure each one, and how do I get website files for like wordpress (for example) to the nginx server, and to have nginx talk to the php container? I understand I need front end and backend ports, so like 80 -> 8081. But I keep getting lost when I try to progress beyond this point.