First take a look at this particular post:
Now that you have some understanding take a look at this one:
A Gentle Introduction to Scikit-Learn: A Python Machine Learning Library - http://machinelearningmastery.com/a-gentle-introduction-to-scikit-learn-a-python-machine-learning-library/
It introduces Scikit-Learn, which is the go-to Machine Learning library in Python. You can probably learn a lot from this particular library because it does a lot of practical things that you would take a while to code easily. It also has a couple sample data-sets, which allow you to start testing and learning Machine Learning straight away.