Renaming Backup Folders / Files

Time Machine backup from Apple MacBook to My Passport Externam Hard Drive.
I cannot rename the . backupdb file so as to give it an identity & differentiate between backup files?

I have tried creating a descriptive folder and to move the backup file into the folder but I get a message saying that the process of moving the file is not supported?

So how does one organise backup files saved to My Passport?