SuperWolfi,
There are some examples that ship with MStudio that should get you started in DIO control in C#.
You should be able to find them in
C:\Program Files\National Instruments\MeasurementStudio70\DotNET\Examples\DAQmx\Digital\Generate Values\WriteDigChan\Cs
You can also go on-line to www.ni.com/examples and look for some more advanced examples.
I hope this helps, let me know if you have any questions.
Regards,
Juan Carlos
N.I.