Hello @Dnyaneshwar Surywanshi ,
Thanks for your query. The error message indicates the corresponding modules are not installed.
Those PowerShell Cmdlets are available when you install MARS Agent.
Try to download the installer from here https://learn.microsoft.com/en-us/azure/backup/install-mars-agent#download-the-mars-agent
Once MARS Agent gets installed in the default folder on the machine , now open the PowerShell prompt and run the commands.
Additional references:
https://learn.microsoft.com/en-us/powershell/msonlinebackup/overview?view=msonlinebackup-ps
https://itproguru.com/expert/2014/01/inside-windows-azure-online-backup-using-powershell-step-by-step/
If the above information helps , make sure to "Upvote and Accept the answer"