I have read that Erlang has a built-in webserver (YAWS); I am developing Erlang using the Eclipse plugin Erlide, I was wondering how I could access such a webserver, for example for running a simply 'hello world' PHP script; just for starting.
Yaws isn't built into Erlang — the built-in web server in Erlang is called inets. You can find more information on Yaws at the Yaws website, and you can find all the details of its PHP support in its PDF documentation. If you run into any trouble getting started with Yaws, you can ask for help on the Yaws mailing list.