Creating and populating www for hosting

Hi there,
I’ve installed HA on spare raspberry pi 3. Very impressed so far, it’s been seamless. I’m looking forward to hooking up some sensors to the system.

I want to add some assets (for the picture element card). I’m following HTTP - Home Assistant but I don’t see how to create this folder nor how to populate it. ssh doesn’t seem to work, nor does sftp.

How do I go about creating this www folder?

Install the SAMBA and/or SSH Web Terminal addon(s) for remote access to your file system.

Thank you! I searched for it but didn’t realise I needed to switch ‘Advanced’ on.
And then spent a few hours fiddling with the config to get rid of the 401 error, which turned out to be browser related (FF linux, 'enhanced tracking proteection must be removed, howto).
All sorted now, I can use ssh from the interface.