Do you have a sound card that Cubase recognizes? Did you read the setting up manual for Cubase so you can get past square one?
The manual for Vienna Ensemble is in the User area > Software then click on the link under Vienna Ensemble. However, if you did not register your software you won't get a link to the manuals. Did you view as many of the videos, starting from square one on how to load the samples on to your hard drive? The videos are a MUST! Go to User Area > Overview > Videos the Quick Start
Be sure when installing the samples from the VI DVD to choose Cubase's VST Plugin file in the first dialogue boxes that come up early during installation. Again watch the Videos on this web site that Paul narrates, they are really the numero uno step you must take.
for any issues with Cubase, write to the Cubase support staff-you'll have to give them the nitty gritties though-more than you've done here. Also read on the www.steinberg.net bulletin board. You will want to regester there. Before you do, I would suggest that you get Windows to give you your system configuration, save it to a text file and pull out the important stuff so you can give that at a moment's notice.
After all the software and Libraries are loaded start up Vienna Ensemble and then Cubase.
Once Cubase recognizes the VI Libraries and software you will open an empty project in Cubase (don't use their templates at this point) go to Devices on the Cubase menu bar, choose VST instruments in the drop down and click inside the empty longer rectangle to the right and choose Vienna Ensemble. Once that loads after a few seconds you will have your first midi channel input set up and you can load instrument samples into Vienna Ensemble
Be sure to snoop around on YouTube as Steinberg has about 16 tons of video tutorials up there. Vienna Symphony videos are Again, the most important key to getting you started and you did not say you had looked at those[:(]