Very good. Its seems that I am not used to find and mount cdrom. Usually it gets mounted automatically. I don't know why, I was looking for a folder. Here is what I have done.
cd-info version 0.79 i486-slackware-linux-gnu
Copyright (c) 2003, 2004, 2005, 2007 R. Bernstein
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
CD location : /dev/cdrom
CD driver name: GNU/Linux
access mode: ioctl
System : Win32
Volume : VBOXADDITIONS_3.2.10_66896
Volume Set :
root:# root:# mkdir /mnt/cdrom0
root:# mount /dev/cdrom0 /mnt/cdrom0
mount: block device /dev/hdc is write-protected, mounting read-only
Then once in the /mnt/cdrom0 folder, I was able to install guest additions using:
root:# sh /mnt/cdrom/VBoxLinuxAdditions.run
If I may ask another question. I would like to know how I can increase the size of the display, so that it fits completely my screen. When I do enter full screen mode, it will enter full screen mode exept that the desktop will occupy only half of the surface of the display.