Let’s try the quick method first and if that does not work I’ll give you the step by step manual method.
*Pardon if my steps are a bit off, I’m not to familiar with Server 2012 Server Manager.
Launch Server Manager
Under Manage menu, select Roles and Features
Select Role-Based or Feature-based Installation
Select .NET Framework 3.5.1
Check the box for “Windows Communication Foundation HTTP Activation”
Click Ok (or Next)
Install
Below is a screenshot of the feature you want (Screenshot taken from a Windows 7 machine). After installing, refresh IIS and verify if the mappings are installed. If not, let me know and we’ll go through the manual process.