Retrieving the openSUSE Disk Image
In contrast to other virtualization tools I've used, VirtualBox allows me to mount a DVD or CD image file (often an .ISO file) directly. There is no need to burn the image to physical media and add the physical CD drive as a virtual drive. It just works.
Go to http://www.opensuse.org/en/ and review openSUSE and licensing terms. Navigate to the Download website area[md]in this case, accessed via the big Get It button. You next challenge is remembering if your computer supports a 32- or 64-bit OS. Virtual Box is powerful enough to offer support for both if your hardware supports a 64-bit OS. Click the Download button once you've decided which version to use. While you wait, consider downloading documentation from the same page.