Steve,
My experience with Virtual Box is using Linux host computers rather than Windows, but I have the following observations.
1. RTFM
https://www.virtualbox.org/wiki/DocumentationDownload the PDF manual. What you need to know is described in there.
USB Support - Section 3.11
Shared Folders - Section 4.3
Virtual Storage - Section 5
Virtual Networking - Section 6
If you haven't done it, install the Guest Additions
2. Keep in mind that the Guest computer functions as a separate networked computer, with the Host computer effectively the router. So make sure that the Guest sees the Internet. This should be automatic using the default NAT (network address translation).
3.. The fact that you are using a Windows 7 host means that your hardware *might* be marginal for virtualization. If you are using an older CPU it may not have the support for hardware virtualization and only support software virtualization which is much slower. If this is the case, then it may be a purely academic exercise to get a Virtual Box working however the computer may not have the resources to run it effectively (i.e. S...L...O...W). I know this first hand when I used a converted ASUS Chromebox with a Celeron CPU which had minimum hardware virtualization support. With a modern CPU using VT-X technology, the Guest OS can run effectively at native speed. I have a Windows 7 Guest computer running on a recent Dell i5 laptop to run older 16-bit Windows applications and it runs just as fast as native applications.
3. Also, make sure you have enough memory between the host machine and the virtual machine, usually what is allocated for the virtual machine is not available to the host. Hard drive space is also needed, but these days it is not an issue because drives are so large.
You are going to have to solve these problems on your own, no one except you are going to know the resources you have on your computer, the issues you are facing, and what you are trying to accomplish. So read the documentation and understand it first.
David