Learn docker, specifically building containers with docker. Learn kubernetes (k3s is sufficient for job training, but I wouldn't go "lighter" than that), take that custom container you built and build a manifest, deploy it, now build a helm chart for it. Pick a cloud provider, deploy it to their instance of kubernetes. Automate as much of the process as you can, write some simple checks that notify you of a failure or continue the deployment on a success.

Start over but make the build more complicated. Don't just do a "hello world", build a custom nginx container. Build and deploy a web app (GitHub is your friend, actually start from code and build a container), a database, and a Lets Encrypt container. Get them all working together, make sure you cut an SSL cert for your app. Think about what you would want to test at this stage: is it reachable over localhost, is it presenting the cert properly, etc. Automate those tests, make sure they alert you. Deploy it to kubernetes when everything passes your tests. You see where this is going I hope, do that process again but in kubernetes. Starting with building manifests and helm charts. Write your tests, make sure they include rolling that SSL cert. When the tests pass deploy everything to your cloud provider of choice, run the tests again.