Import pfx certificate

how do i import a .pfx certificate into xibo running on docker on ubuntu

i followed the following guide

https://xibo.org.uk/docs/setup/xibo-2-1-0-with-docker-on-ubuntu-18-04

but letsencrypt dont do local certificates so generated a .pfx from our windows ca onsite .

sorry if this is a really silly queary but im still getting used to comand line ubuntu and docker

thanks for anyhelp