Free place to host a private beta version of a website?

been doing freecodecamp
almost have web design certificate
my martial arts school needs a web page
i volunteer since i need the practice and may look good in portfolio

but, i need to run everything by the owner before it is published.
however, he is NOT tech savvy (still using old Motorola i530 from Nextel).
where can i build a workable prototype which he can use/click/browse but other people can not see it?

don’t really have a portable rig though.

thanks for the help @camperextraordinaire but we may have both been overthinking it.

amazingly the simplest free answer came from 4chan (which is usually NOT helpful)
just save the .html file and send it to the owner and he can open it in a browser.

yeah, all the links are to existing sites. and the images are hosted on imgur.
the whole unzipping and index thing would take a week to teach him. lol