Use the below syntax:
docker exec -ti <container_id> <command>
To check the container id, run docker container ls
command in the console.
Examples:
docker exec -ti date
docker exec -ti 011f0b0f68ce echo "hello world"
docker exec -ti 011f0b0f68ce mkdir -p "/home/databox"
Reference - https://docs.docker.com/engine/reference/commandline/exec/