To really understand Docker, it matters more to see the overall workflow than to memorize commands. Image is the template, container is the running instance, Dockerfile is how you build an image, and Compose is how you manage many services at once — connect these four ideas together, and you'll be able to handle Docker projects with a lot more confidence.
Summary
• docker run starts a container.
• docker ps shows container status.
• docker stop/start/rm manages containers.
• Dockerfile lets you build your own image.
• -p does port mapping.
• Volumes keep your data from disappearing.
• Docker Compose runs multi-container apps.
Info
As a next step, try a project that runs a Node.js app + PostgreSQL database with Docker Compose. Once you get there, you'll be able to build real-world backend development setups with Docker.