Avanti can create new image files, essentially creating new virtual disks, on startup.  To create a new virtual disk, select image file in an unused disk location and click the browse button […].  Navigate to the desired host system folder and type in the new disk file name.  A disk type selection box will be displayed, as shown here.  If a custom disk size is required, click the Custom disk size button and enter the desired size in Megabytes (M) or Gigabytes (G).