HTTPS and Reverse Proxy?

So I have my main webserver 192.168.1.31 (Virtualmin). Port 10000, 80 and 443 are forwarded to 192.168.1.31. I also have 192.168.1.46 running Nextcloud on port 80, and 192.168.1.53 running ONLYOFFICE. As for now under "Proxy Website" I have them linked with http://LOCALIPADDRESSHERE Now for my question! How do I get them to run with HTTPS. I have certs for them, do I have to configure nextcloud and onlyoffice to run port 443 or is it something I can do in Virtualmin like under sites-enabled? How do I get a proxy to have HTTPS? Thank you!