Vitualbox is not working

Hello,

i download VB in the Ubuntu Software Center and install it. i open it and made a vm on then open it up and it shows:

Failed to open a session for the virtual machine Windows Vista.

AMD-V is disabled in the BIOS (or by the host OS). (VERR_SVM_DISABLED).

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: Console
Interface: IConsole {8ab7c520-2442-4b66-8d74-4ff1e195d2b6}

please help this is my first post on ubuntu forums.