first off - install git. Just do it even if you're not using right now.
new to bash on osx? copy [[https://github.com/patarleth/emacs-shell-config/blob/master/bash/.profile]] to ~/.profile and
editing your bash_profile etc? The only thing interesting in my profile is my git integration and even that is very copied from god knows where ;)
So copy the git_prompt() function, and call it in your PS1 var chech the file above to see how I do it.
My PS1 has
1. who and where you are logge into
2. time and date
3. git branch and commit status 2 ahead, 1 behind etc
4. dir path
5. number of files and sum of their size.
6. color!