The following example configures a virtual host for www.example.org on node node1.example.org, and enables php on the webserver.

node 'node1.example.org' {
    include webserver

    webserver::virtualhost { "www.example.org":
        enable => true
    }

    webserver::module::enable { "php":
        enable => true
    }
}

You can also realize() the Module_application["php"] resource directly, but that requires you have knowledge of the lists of stock and package modules and applications:

node 'node1.example.org' {
    include webserver

    webserver::virtualhost { "www.example.org":
        enable => true
    }

    realize(Webserver::Module_application["php"])
}