VirtualBox: access Windows-host shared folders from Ubuntu-guest
This is the scenario that you run Windows as your host operating system and Ubuntu in a VirtualBox, and that you want to access a specific Windows folder from Ubuntu.
First you have to make sure that have install Guest Additions. From the VirtualBox’s menu go to Devices → Install Guest Additions… This will mount a virtual CD on your /media/cdrom. Normally this folder’s window will show up. As root run the program VBoxLinuxAdditions.run. When the program completes reboot your VirtualBox.