Although an emulator can pretend a virtual machine has a hard disk drive, the so-called hard disk drive (of a virtual machine) is merely a big file to the host operating system.
The first step to set up a virtual machine is to create a image file that will be used as the hard disk drive. This can be done with the program called qemu-img.exe. The following commands (run them in a command line interface) will create a 500MB disk image:
This creates a single file called hd1.qcow2 that will be used to emulate a 500MB hard disk drive for a virtual machine.