Start by making a simple image and make a container of it (I started with a simple python webserver)

Once you grasp basic cli commands and the docker lingo, try pulling portainer and use its web ui.

Next step would be to customize an image.

There is a lot of information on SO, and you can ask specific questions on sites like this one. YT videos are 99% shit. Avoid.

I think docker is so stupidly awesome I nowdays dont want to do anything without it.