If you want to learn Python to work with the Revit API, best start here: http://wiki.theprovingground.org/revit-api. If you're looking for a more general introduction you could start at http://www.learnpython.org or http://www.pythonforbeginners.com. And here's a list with a few more resources: https://wiki.python.org/moin/BeginnersGuide/NonProgrammers.