Docker is professional software and because of that isn’t always the most intuitive thing to use.
The first big thing to get your head around is that there is no GUI. Everything you do to manage docker is through the command line. If you really want to, there’s some third party GUI software for managing Docker, but I haven’t used it in the 2 years I’ve been using Docker.
Once you’ve installed docker, there’s a little bit of setup required to make it run smoothly. The Docker Docs page on Linux post-installation steps has detailed instructions on how to do that and how to run a test container