For running an application you need an OS, RAM, CPU, etc. It may be in a full-stack domain, or cloud domain, or any other domain. You can say docker is a light weighted OS. You can use docker for every individual application. The first thing you need to do is configure docker in your system. After that, go to the docker hub and search your required image. For example, you need OS for python, then go to docker hub and search an image for python and use it.
If you are a beginner on docker, then you can go through the below youtube video.