OSX interactive Python

 Start up a Terminal command prompt. You can find the Terminal application through Spotlight, or navigate to Applications/Utilities/Terminal. To start Python, type

python

at the command prompt and hit enter. You should see something like Python 2.7.1 (r261:67515, Feb 11 2010, 00:51:29) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>>

The  indicates that you are at a Python prompt. Exit the Python prompt by typing

exit

and hitting enter. Now you're back at the OS X command prompt (which looks something like ). 

Success!
Practice these steps until you feel comfortable navigating to a command prompt, starting Python, and exiting Python.