Anyway, here's what to do.
First pull the mongo docker image.
To check that it's there after everything is done you can run docker images and you should see something like this.
REPOSITORY TAG IMAGE ID CREATED SIZE mongo latest 282fd552add6 2 days ago 336.1 MB redis latest be9c5a746699 5 weeks ago 184.9 MB
In this case I want the connection to Mongo DB to be available so I'm going to bind its local port (27017) to my host. I'm also going mount my local data file in the container so it will save its data my local folder.
The --name flag gives the name that you'll see if you run docker ps to see the running containers. -p 27017:27017 makes it available to my host machine via localhost:27017. -v $PWD/data:/data/db mounts the data folder in the directory where I ran the docker command inside the container at /data/db. -d says to run it as a daemon. Finally the last argument mongo identifies the image for the container.
At this point MongoDb is accessible from my host machine, so, using pymongo I can connect to it using something like this.
And that's it.