Define Oracle back up to the external medium

Hi,

I would like to set up back up for my Oracle DB on the external medium (FTP)?

How can I proceed, which parameters should be set in the init<DBSID>.sap ?

backup_dev_type = stage

archive_stage_dir

remote_host

How can I set “remote user and his password and check that <SAPSID>adm and SAPService<SID> have write access to the external medium?