On Windows, pip lives in C:\[pythondir]\scripts.
So you’ll need to add that to your system path in order to run it from the command prompt. You could alternatively cd into that directory each time, but that’s a hassle.
See the top answer here for info on how to do that:
Adding Python Path on Windows 7
Also, that is a terrifying way to install pip. Grab it from Christophe Gohlke. Grab everything else from there for that matter.
http://www.lfd.uci.edu/~gohlke/pythonlibs/