Hi,
'DB restore utility' is to just restore the compressed back file of AttendHRM. if you want to use an old backup file in new AttendHRM version(3.6), just restore the backup file with the restore utility and place the restored ITAS.FDB file in 'Data' folder of 'AttendHRM Installation folder '. By Default the installation folder would be in Program Files/Program Files (x86) of C drive.
Hope this helps.
Rijo