When it says "Run command", copy and paste the command part into a CLI, such as Powershell or the command prompt (make sure Git is in the path).
- Make sure Git is installed.
- From http://gnuwin32.sourceforge.net/packages/util-linux-ng.htm, download the binaries and dependencies zip-files.
- Extract them and copy the contents of the bin-folders into your Git installation's bin folder, for example
C:\Program Files (x86)\Git\bin. To find out where it is runwhere.exe git. - Set root directory to where you want to clone git-flow.
- Run
git clone --recursive git://github.com/nvie/gitflow.git - Run
cd gitflow/contrib - Run
msysgit-install.cmd "C:\Program Files (x86)\Git"(remember to use the same git installation folder as above). - Test that it's working by running
git flow help.

Thanks