If you do not have Git installed, please install it.
Download from
http://msysgit.github.io/
When going through the installation, make sure to select "Run Git from the Command Prompt" at one of the installation steps.
If you have 10.9 or later open a command line and install git using:
xcode-select --install
Then try to run git from the command line to see if it was installed. If that does not work, try to download and install Git from:
http://git-scm.com/download/mac