This tutorial discuss how you can enable (Internet Information Service) IIS in Windows 7 or Windows Vista. I have provided screen-shots so that you can easily understand.
First go to control panel and select Programs.
Then select Internet Information Services. (If you plan to run web services you have to select ASP.NET under Application Development Features as following figure)
Now you have enabled IIS and try "http://localhost" in your browser and you will get following page.