How to run project on gitlab

I’m so amateur in GitLab and CICD.
I created a project in my GitLab account then I created a .gitlab-ci.yml file in my project.
In the .gitlab-ci.yml file, I used 3 stages(build - test - deploy) and when I run the pipeline, everything is fine and the pipeline passed.

Now I created a simple(Hello World) java project in my system. And want when I push my codes on GitLab, my “hello world” application runs and I could see the project’s result which is shows “Hello World” in the console.

Please guide me
Thanks in advance

Any Idea?

Isn’t there really anyone here who can guide amateurs like me?

What can I do guys?