I'm talking about the document root of the reverse proxy server. How do I set it?
Use the DocumentRoot directive and a <Directory> section that matches, just as your defauly configuration surely already had.
And do I have to also run the server that I want to put behind the reverse proxy for this to work, or is that not necessary?
The proxy server isn't starting it for you, so yes it's necessary for you to start it.
And please also tell me if I have the reverse proxy configuration stuff done correctly in the httpd.conf file. I'm attaching it to
Looks wrong, it is proxying back to port 80.
Along with that, I also want to know how to get a subdomain so I can use that and its IP address for my virtual host and ProxyPass settings as needed. I'll get a free subdomain and instead of a top-level domain if that's okay for this.
Find a provider of free subdomain DNS. Determine your computers IP address. Fill out the free providers form and associate the two.
What I'm doing is having the Apache httpd listen on port 80 while I have the server I want to put behind the reverse proxy listen on port 8080. When I tried to put both on the same port, and tried to run the server I'm trying to proxy, I got an error on that
server saying that I'm trying to access a port I have no permission to access.
Generally you'll need to pick different ports.