Right, I've not read the tutorial, so I may be repeating it, but I have installed PHP on a number of platforms.
what operating system are you installing on?
you need to edit your "hosts" file.
In windows its in the windows folder and called "hosts.sam"
on linux, I think it's in your home directory.
you need to add this line to the bottom of the file:
127.0.0.1 localhost
then you rename the file to "hosts" remove the ".sam"
make sure apache is up and running, then go to http://localhost in your browser, it should work fine.
Matt