The first step is to create a file to contain an image of the complete virtual disc. This could be a large file containing a lot of empty space and clogging up your physical hard drive. Fortunately, QEMU allows you to create a "copy on write" (COW) file that is only as large as necessary and expands as your virtual disc contents expands.

Create a subdirectory of your home directory and create the image. The Linux commands create an expanding image file with a maximum of 4GB are:

$ cd ~
$ mkdir puppy
$ cd puppy
$ qemu-img create puppy.qcow -f qcow 4G
Formating 'puppy.qcow', fmt=qcow, size=4194304 kB