First you will need to create an Empty site collection in SharePoint using stsadm.exe, this is not the same thing as creating a blank site using Central Administration or blank site using stsadm.exe.
STSADM.EXE -o createsite -url <url-to-site-collection> –ownerlogin domainuser -owneremail <email-address>
STSADM.EXE –o createsite –url http://servername/sites/emptysitename/ –ownerlogin yourdomainuseraccount –owneremail email@example.com
Once the empty sight is created you will need to use stsadm.exe to import your current backed up site.
STSADM.EXE -o import -url <url-to-site-collection> -filename <path to backup file> -nofilecompression
STSADM.EXE -o import -url http://servername/sites/EmptySiteName/ -filename d:savedmyfileheremysite.cab -nofilecompression
Of course this all will need to be done from the SharePoint Server Frontend and you must have administrative rights to the site you created.
Stsadm.exe is located under the installation directory for SharePoint normally
C:Program FilesCommon FilesMicrosoft Sharedweb server extensions12BIN
So you may have to browse to there from the command line to be able to run
stsadm.exe unless the path is added as a path variable in you server start up