virtualbox.org

Hello, I am completely new to virtualization.On my windows XP system, I downloaded a software package that is a so-called"virtual appliance", this image is specifically for Virtualbox and is a "vdi" file. However, when I open Virtual Box ->File->Install Virual Appliance , it only accepts OVF files. What am I missing? Thanks !

You only have a virtual hard drive file, not the full settings for that VM. If you can find them, you can create a new VM and configure it to use those specifications. Else you need to find them through trial and error.
You have to add the VDI to the Media Manager too, so open that through File > Virtual Media Manager, click Add from the Hard Disks tab and browse to where you saved the VDI, then add it. Now you can select that hard drive as existing one for a new VM.