-Install default debian release (jessie) in a Virtual Machine file with
-3GB disk size (including Grub as bootmanager in MBR of the virtual disk file):
+Install default Debian release (jessie) on /dev/sda3 and install bootmanager
+Grub in MBR (master boot record) of /dev/sda and use /dev/sda3 as system partition.
+Use specified mirror instead of the default (http://http.debian.net/debian) one.