You should see an image that is made up of the non-green portions of your foreground clip, overlaid onto your background clip. It should look something like what you see here, but it may look a lot different, depending on your source clips. A little bit of halo around your subject is common with DV, because of it's low chroma resolution. You can minimize this effect by adding a backlight to your subject, to keep the back edges from being really dark and setting the subject off from the background.

We're just about done now. If you hate the results, you may want to go back and tweak the settings on the VKey Filter to get a better key. If you select a higher value for cutoff angle, more green will be keyed out, and a lower value will key out less green; in case some of your subject has been compromised. All we have left now, is to export our composite.