@madiha, your version of Win 8.1 does not allow Remote Desktop Connections.
Extract from http://windows.microsoft.com/en-au/windows/remote-desktop-connection-faq#1TC=windows-8
Which PCs can I connect to using Remote Desktop Connection?
You can use a PC running any edition of Windows XP, Windows Vista, and Windows 7, or a PC running Windows 8, Windows RT, Windows 8.1, or Windows RT 8.1 to initiate a connection. But the remote PC must be running one of these Windows operating systems:
Windows 8.1 Pro
Windows 8.1 Enterprise
Windows 8 Enterprise
Windows 8 Pro
Windows 7 Professional
Windows 7 Enterprise
Windows 7 Ultimate
If you use Win7 Pro or Win8/8.1 Pro you will have no issues running RDP. As @gerlandog has stated, Win 8 Home has only 1 RDP connection which does not help you run both at the same time.