How to map a folder in our local file system as a Workspace in Alfresco repository.
OR
How to map a folder to a workspace.
BY CIFS we can mount a new Network drive. But my requirement is with the existing Folder (having some documents) how to make it as a repository workspace ?
You can't. You'll have to move the documents into Alfresco via the mapped network drive for Alfresco to manage.
Alternatively you can always use Explorer offline file access to sync network drive (Alfresco via CIFS) to local folder. However, this is known to cause issues with versioning turned on in Alfresco.