Getting started: instructions in the README not detailed enough

[corinnaSchultz]

I'm on mac. I didn't have python on my machine (I'm not a python user), so I used homebrew to install.

brew install python
pip3 install --user git-gud
(got an error message "error checking the latest version of pip". Some googling led me to try:)
python -m pip install --upgrade pip
(python not a command. I tried instead:)
python3 -m pip install --upgrade pip
(that worked so I tried again:)
pip3 install --user git-gud
(that succeeded without errors, so next step)
git gud
(got an error message from git "gud is not a git command")

(I created a new directory and changed into it and tried:)
mkdir gud
cd gud
git gud init
(got the same error message from git)

I'm stuck.
I have no idea how to run this. Is there a change I need to make to PATH?