Since you are just getting started with your digital output application, I would recommend going to the Example Finder in LabVIEW (Help >> Find Examples) to find a VI to try out. Are you using NI-DAQmx or Traditional NI-DAQ? If your device supports it, which you can check at http://www.ni.com/support/daq/versions.htm then you should use NI-DAQmx. In particular, a good example to look at in the Example Finder is Write Dig Chan found at Hardware Input and Output >> NI-DAQmx >> Digital Generation. In order to use lines 0 through 5, you need to edit the channel parameters to say DevX/port0/line0:5 where X corresponds to your device number. Then, you need to remove two active elements from the Data to Write array by right clicking on the array twice and selecting Data Operations >> Delete Element.
Hope this helps,
I have modified the example I referenced previously and attached it. I tested it, and it works correctly.
I'm sorry for my late reply. At the moment I'm stuck with other chores at work. Not been able to continue my work with LabView. I'll try to give you a real reply soon.
Thanks for your help and for waiting.