How to allow windows 7 to access external hard drive, when running in virtual box on MacBook Pro?

Hi,

As a newbie to running Windows in a VM, I've managed to install VirtualBox and even get Windows 7 installed and running on the MacBook. SO far so good...

...but, when I go on File Manager, I can only see the 'c drive' and what I think is the partitioned chunk that it boots from - no external hard drive or even a usb stick when I plug that in. Any ideas on how to get the VM running W7 to recognise and access those peripherals?

Many thanks