Many times it is necessary copy or send files to your docker container instance.
In my case was with IRIS JDBC driver.
Docker has this recipe for this (credits to https://docs.docker.com/engine/reference/commandline/cp/):
docker cp [OPTIONS] CONTAINER:SRC_PATH DEST_PATH|- docker cp [OPTIONS] SRC_PATH|- CONTAINER:DEST_PATH
But to copy you need your container name. Write this command for this:
docker ps
In my, my-iris is the container name.