Start to sale videos of masterclass

I already have a small wordpress website.
I already started to share some videos, for free, via my youtube channel, that I use on my webpage : www.apneiste.fr/les16leviers.
I want to add some new videos, but a restricted access, that people who paid for it, could see on my webpage.
So I need to have a way to collect this money and a backoffice to manage which video is for free, and which video request a payment.
I need also to “rebuilt” my website. I mean for this just to adjust some sizes of photos or videos to offer a most beautiful website.
It’s not for a big market. I’m talking to french experienced freedivers. I will not pay a lot for this, as I can’t hope a good business with. So I’m searching a simple way to manage it.
thanks for your offer.