Using ST Integration in a docker instance

So I have installed and running a HA inside a docker container, and its working great. I want to integrate my ST to the HA instance, but I am hung up at the point with trying to get a certificate to import from lets encrypt, so i can attach my webhook to that(Im not using the cloud service, as I already have a DynDNS)
I am very green to docker implements, as obviously I cant just SSH into the docker instance(or can I)
If someone has a how to for doing this with a docker install, that would help me immensely!