backup and Restore sites[SharePoint]

For backup use :
step 1:
cd C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\BIN

Step2 :
stsadm -o backup -url "http://Siteurl" -filename C:\Backup\BackupSite.bak

For Restore :

stsadm -o restore -url "http://retsoredsite" -filename C:\Backup\BackupSite.bak