Steps to create a new FTP user
1. Login to plesk
2. Go to domains > domain name
3. Click FTP access
4. Click "Add an FTP Account"
5. Fill the details and Press OK
Note: Home directory of "FTP user" could be appropriately selected to restrict access of the new FTP user to a particular folder.
Steps to enabe SSH access to an FTP user
1. Login to plesk
2. Go to domains > domain name
3. Click FTP access
4. Click the required user
5. Set "Access to the server over SSH" as "/bin/bash"
6. Press OK
Please note that only main FTP user of a plesk domain can have ssh access. Additional users cannot get SSH access.