windows 8.1 - Error "VT-x/AMD-V hardware acceleration not available on your system" while trying to run Virtualbox

I have to run Mac OS on virtual box for a class and it keeps giving me errors stating

"VT-x/AMD-V hardware acceleration not available on your system. Certain guests (e.g. OS/2 and QNX) require this feature and will fail to boot without it."

If there is a solution, I am not used to windows 8.1 and will need detailed instructions on how to fix it. Thank you