Install terminal services and .NET Framework 3.5 on windows server 2008 2012 r2 standard

Open Server Manager (type in start menu to find it) - or Control Panel - System and Security - Administrative Tools - Server Manager
or Right click My Computer - Manage

Server 2008 :
Click Roles - then click - Add Roles
On the Before You Begin - Click Next
On Server Roles - select Remote Desktop Services - formerly known as Terminal Services
Continue the wizard.

To install .NET Framework 3.5
Open Server Manager
 Click Feartures- then click - Add Features
 Select .NET Framework 3.5 

 Server 2012 :
Mange - Add ROles and Features -- same as above
On 2012 you have to specify additional path to windows 2012 dvd