There's countless Parkour resources on the internet, so much you could forget to actually go out and train. Here's a quick list of some useful links:
Twio-X: the website of the Leipzig Parkour community. They have information about many more spots, a training schedule, news, and real Parkour and freerunning classes.
American Parkour: the main website for Parkour in the USA, with a very active forum, many tutorial videos, and tons of information.
Eat, move, improve: a more general exercise page with a Parkour slant and tons of important advice for training, recovery, and overall health.
Beast Skills: a strength gymnastics website with many tutorials for those who want to turn into muscular beasts.