Win2k backup

I encountered the following error when 1st
running Win2k backup :

Required Media Missing :
There is no unused media available with the selected type.
Add unused media or click cancel to select another type.
Note : It may take up to 60 secondsfor Removable Storage to recognize new media.

Questions :
1) What does it means my ‘unused’ media ?
2) How do I check what service pack has been
installed ?

Pls help.