Apache reverse proxy

I would like a presentation or a document
How do you configure apache to be a reverse proxy?

I would like a screen shot of the step to step for the process
E.g. an application on web server in a secure zone might be http://app.internal.company.com
Apache on outward facing DMZ is to serve that site to the outside world as http://www.company.com/app
Things to consider are:
What modules need to be included in apache?
What directives need to be in the apache configuration file?
What other issues might need to be considered?