1) Download the Debian netinstall CDs
2) Create a new machine in the VirtualBox select Debian 32 or 64 bits (needs to be same arch of downloaded netinstall CD). Select about 512MB of RAM or more and 8GB Hard disc or more.
3) Edit the machine Settings. In the Storage click in the Empty disk under “Controller IDE” and then click in the CD Disk more at right side of screen and click on “Choose CD/DVD virtual disk” and point it to .iso netinstall CD.
4) Click in the “Controller: IDE” and then click “Add Hard Disk” and select the Debian.vdi disk image that was created when you create the Debian Image. This same file is also at “Controller: SATA”, but older Debian images (Woody, Sarge) will not detect the SATA then you can remove the Debian.vdi from SATA.
Now just start the Debian image and it will show the Debian boot image. After conclude the installation you need to enter the Archive debian repositories:
deb http://archive.debian.org/debian-security/ <version>/updates main non-free contrib deb-src http://archive.debian.org/debian-security/ <version>/updates main non-free contrib
Remember to replace “<version>” by “woody”, or “sarge”, etc.