Certificate free et yunohost


I just installed the latest version of yunohost, and I can read and re-read everything I find on the sites,
Impossible for my site to be certified.
I have a domain at free, so xxxxx.freeboxos.fr
I imported my certificate (ca.crt) on my computer, but where and how to put it on the server yunohost,
And how to tell yunohost that this certificate is valid

thank you