Suppose you already have one public Website working on your 2008 Windows server which is probably running IIS7. Now suppose you wish to add a second public Website to run on the same server.
One of the simpler first tasks would be to enter the control panel of the company that administer the domain name that is already "live" and look at whether that Website is using named servers or IP addresses in the “Named Servers” or “Domain Name Servers” or “DNS” entry section. This information will be available in the individual doamins configuration section.
Whatever type of entry they exists there will likely be the same entry you will nned to enter in the DNS section of the new/ 2nd Website you are adding to your server; that’s the public side of things done!
Depending upon your "provider" that entry will start re-routing requests to the IP or Named servers you entered into the control panel of the company that administer the domain name for you.
( If this is only the 2nd Website you are creating it is likely that the DNS entries will be IP values, named servers have names like SS01)
That’s quite straight forward; the second part of the task is to configure your 2008 windows server to host the new domain name, this is when you need to open up the IIS “server”
PHP Applications reference
Let’s suppose the Website you already have running is called ourfirstwebsite.com and that you have now have to add a second Website called oursecondwebsite.com.
The most straight forward way to do this is to add another application by right-clicking Sites then select Add Web Site. In there you can also specify the physical path of the 2nd Application (each Website is termed an Application by ISS) and also set the "host" to "www. oursecondwebsite.com" which will filter all those requests to your second site. Any requests that don't match "www. oursecondwebsite.com" will still go to the default web site (www.ourfirstwebsite.com).
If the second new domain name is going to host an application of some sort then your best bet is to download the latest Microsoft Web Platform Installer, this tool prepares IIS for the installation of Web Applications of different types including PHP apps/sites. Version 3 is below, and a good tip is to watch this,
Tool that prepaires IIS for everything!