SSL/HTTPS; Need help; Owncloud

Hi Guys,

I need a detailed guide to insert a signed SSL certificate.
My last Owncloud installation was already several years ago. Accordingly, my Linux knowledge is pretty rusty.

At least now I have finished installing Owncloud and opened port 443. I can access the Owncloud installation and UCS externally.
Also the client works.

I would like to remove the warning message that comes when opening the website.

There are some very spongy instructions that I can not get on because of my erroneous experience.

If possible, I would like to insert a SSL certificate with wildcard function.

At the moment I’m running version 4.2-3 errata418 (Lesum).

Thanks in advance.