I am a newbie in python. I am using pycharm to run my python code. But in some of python tutorials I saw programmer using windows power shell for python programming. What should I use, pycharm or windows power shell? And also, which version of python I should be using? Currently I am using python 3.4.3
PyCharm is pretty excellent IMO. But it is fine to use a regular text editor and the terminal to do your Python programming too.
I would say if you are doing something small, use a text editor like Sublime Text to write the code, and the terminal to run it (you might learn more).
For larger projects though (when you are out to DO instead of LEARN), an IDE like PyCharm can be very helpful.
Also, Python 3.4.3 is good as long as it can handle the libraries you need to use.