You don't have to be online: 'localhost' is the server on your PC, you get to it using your browser but it isn't online. To prove this to yourself go to 'localhost' with the phone line unplugged.
That server info is for if you be use the server as a live server (i.e. accessible from outside) but you are using it for local testing so for the server name use the local 'loopback' IP address 127.0.0.0 .
What file extension are you giving the 'Hello web' test page? Is it .php?