This is the theory. Don't hesitate to follow the different parts through this series of articles:
part 1 - part 2 - part 3 - part 4
Should you actually want to implement what you've learnt and get a little bonus, you can get a very affordable paid version at this link. I'm one of those people who never apply anything if there is no-one actually waiting for something from my side, so I offer you a little mind trick to actually implement something :)
