metulburr and snippsat pretty much gave you the details to get set up to run Python properly. If I may, can I offer a few tips too, I think their a good idea...
... As pointed out you add Python to the PATH so your system can find it --- C:\Python27
... As well, snippsat mentioned adding --- C:\Python27\Scripts
--- this helps to locate scripts that might be needed depending on the packages installed.
... I like to add my own Python scripts to the PATH as well --- C:\MyPy
--- short, sweet, and I avoid spaces in the name.
So, this particular PATH addendum would be --- ;C:\Python27;C:\Python27\Scripts;C:\MyPy
But, it does get old typing out the path to your scripts, especially when you have 5 thumbs on each hand like I do, that is why I also use a console enhancement to make using the command prompt a bit easier. Here's 2...
Both are free and portable, Console is my favorite. I like having tabs, and more importantly you can have the default startup directory be your python (.py) scripts directory.
... I start Console in -- C:\MyPy> -- to run a script I type -- >python myscript.py -- and hit enter.
... It's nice to be able to open a second tab -- C:\>, type 'python' and now Python is running too --- >>> print 'Hello World!'
PowerShell may do all this too, not sure.
I have not tested this and I may have misunderstood but, if you add .PY and .PYC to PATHEXT (not PATH), if you have a standard Python install and Python registers these files, you may not have to type the extension only the name of the script --- >python myscript (rather than >python myscript.py). I use portable Python so nothing is registered and I've yet to confirm this.
Anyway, hope some of this is beneficial to you.