How to edit Aspnet_isapi.dll mapping in IIS 7.5?

I am trying to host WCF service svc files 开发者_运维百科on IIS. Whenever I browse the svc files through IIS hosting it just shows the text contained in svc files in the browser. I went through few msdn links to change the mapping of dll but those documents are for IIS 6.0 and before. Its the first time I am working on IIS and I am not getting how to add view the dll mapping in IIS 7.5 manager.

http://msdn.microsoft.com/en-us/library/aa751792.aspx

Follow the Windows Vista part to enable Windows Communication Foundation Activation Components under .NET Framework 3.5.1.