I found where the configurations had to be made: etc/apache2/sites-enabled/000-default. I think older versions of Apache had to be configured in httpd.conf, but this is no longer the case (not sure!). I also had trouble configuring it correctly.. I'm still not 100% done, but the reverse proxy is working. As for the domains, I just wrote ip addresses in the conf file as opposed to domain names.. right now it only works for one server, not sure how to add names, example: 192.168.0.1/example
I'm not near the machine now, so I can't show the conf file at the moment.
Not 100% solved I guess!