How to add files to external hard drive with pro ftp

I am a new user of diet pi . I am using diet pi as a plex media server and I added my media to an external hard drive . I wanted to add more media to my external hard drive using proftp but when I access ithe pi all I see are folders that say video, music etc. How do I go about getting to the external hard drive and adding my new files? Thank you for your help.


many thanks for your message. I recommend to have a look into our online docs
There is a section about changing destination directory