Hi @Mechah - I split this off into a new topic, that way it shows up in the forum's search a bit better. Here are a few screenshots to get you set up with shared folders:
1. Install Guest Additions
After clicking on the CD icon in the lower left, click on "Run Software" in the upper right. Enter the password when prompted.
When installation is done, your screen should look like the following. Follow the prompt and press "Return"
2. Set up a shared folder
In the menubar, select 'Devices' -> 'Shared Folders' -> 'Shared Folders Settings' (note, this might be slightly different on Windows or Linux systems, please check the official VirtualBox Docs):
Click on the green plus sign/folder on the right side of the window, you should see a new screen prompting you for info:
Click on the 'Folder Path' input, and using the file browser (by selecting the option 'Other...'), select the folder you want to share with the VM. I chose my Desktop ('/Users/matthew/Desktop' on my Mac). Make sure to select 'Auto-mount' and 'Make Permanent', if you don't want to repeat these steps every time you launch the VM. Also note, the 'Folder Name' option (which VirtualBox will auto-suggest a value for) is the name of the mounted folder inside of your VM. From what I understand, VirtualBox will always prepend an sf_ to that value ("sf" for "shared folder"). So in this case, the folder name will be sf_Desktop. The full path when mounted is /media/sf_Desktop. If I chose to name the 'Folder Name' something like 'foo', then the mounted path would be /media/sf_foo.
Click 'OK' on both dialogs to save your changes.
3. Reboot
Click the gear in the upper right of the screen, then 'Shut Down...', then 'Restart'.
4. Enjoy!
Once you are rebooted and logged in, you should see your shared folder in the file browser (the icon on the left bar that looks like a file cabinet:
The files there are the files on my Mac's desktop! I can also access the mounted folder via the Terminal at /media/sf_Desktop:
Hope that helps!