How to add domain name in IIS

Hi,
I am working on IIS to host asp.net web application on local machine. So I want to add domain name in IIS when i added website for hosting using IIS . But i don't have to add domain name so please tell me how can i add it without port number like as www.example.com or show uri same as http://localhost/TestDownload/download.ashx

Thank you in advance.