Trying to set up docker container for postgres

Question

I just downloaded docker and can't find any documentation to help me with this.

I did

brew install docker

Then I'm following a tutorial where I'm supposed to do

docker pull postgres

But I get

Using default tag: latest
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

To get the docker daemon running I've tried all sorts of things and keep getting errors.

sudo dockerd        
sudo: dockerd: command not found

docker run -p                                                                                      
flag needs an argument: 'p' in -p

docker run -p 8050:8050
"docker run" requires at least 1 argument.
See 'docker run --help'.

Usage:  docker run [OPTIONS] IMAGE [COMMAND] [ARG...]

Run a command in a new container

launchctl start docker doesn't fix it.

I'm sure there is some basic command I just have no idea about? Can you please help me.