Philipp,
The best way to get started is to decide if you want to use traditional NI-DAQ or NI-DAQmx. Recently we released NI-DAQ 7.1 which provides NI-DAQmx support for the PXI-6508. In my opinion, NI-DAQmx is more efficient and much easier to use.
To get started with examples, simply launch LabVIEW and go to Help>>Find Examples. Then expand Hardware Input and Output>>DAQmx and select the appropriate digital group for your application. This should help get you started.
Please repost if you need addition assistance. Good luck with your application!