Use below syntax:

docker exec -ti <container_id> <command>

To check container id, run docker container ls command in the console.

Examples:

• To print date in the console - docker exec -ti date
• To echo Hello World in console - docker exec -ti 011f0b0f68ce echo "hello world"
• To create a directory inside container - docker exec -ti 011f0b0f68ce mkdir -p "/home/databox"

Reference - https://docs.docker.com/engine/reference/commandline/exec/