There are tons of YouTube tutorials for docker.

I learned by finding what I wanted to use docker for and following tutorials. Learned along the way.

I recommend setting up portainer so you can have a user interface with docker. Look up portainer and follow their tutorials to set it up.

Just using komga and komf and I am very happy. Get my manga from FMD2 docker container. Volumes from Nyaa.

Immich easy. The rapid updates have been great. Almost never hit issues and my family loves it for photo sharing.