What is the processor of the computer that you installed Visual Studio on? Your processor has to support Second Level Address Translation (SLAT) in order to run Hyper-V (SLAT is found in Intel core i3, i5, and i7 processors). If your processor is an AMD processor, SLAT is supported if the processor is a third generation Opteron processor or later. If you're sure you have that, check out
How to enable Hyper-V for the Windows Phone Emulator for the procedure to get Hyper-V installed and configured.
If you installed Visual Studio on a computer with a Core 2 Duo processor, you are unfortunately s.o.l. (sold out of luck), as the Core 2 Duo does not have support for Second Level Address Translation. If this is the case, however, you can debug your programs on a WP8 device (with no problems), but not on the emulator.