Viewing shared folders within virtual boxes can be a tricky task. Copy contents between shared folder among host and guest OS can be extremely useful. Below is a quick tip to access the folders.
Step one is to set up the virtual box manager
With Guest Additions installed you may now go ahead and define the shared folder(s). From the VirtualBox's menu go to Devices → Shared Folders. A dialog will show up. In this dialog you can specify which folder from your Windows system you want to share with your Ubuntu. Press the button with the + symbol to add a new shared folder in the list. You will have to specify a Folder Name for each folder you add.
Next you have to create a mounpoint, that is, a directory in your Ubuntu which will reflect the shared folder from Windows:
# sudo mkdir /media/windows-share
Of course you may choose an alternative path for your mountpoint. With your mountpoint created you can now mount the shared folder, like this:
# sudo mount -t vboxsf folder-name /media/windows-share
Where folder-name will be the name you assigned for this folder when you were adding it in the shared folders list.