There are a number of examples which ship with the NI-DAQ driver which perform an analog output using the WFM commands. If you installed support for Visual C or Visual Basic when you installed the NI-DAQ driver you will find examples in the \Program Files\National Instruments\NI-DAQ\Examples directory. You didn't mention what language you were using; however, if you look in the VisualC\ao subdirectory you will find manu examples which demonstrate generating a waveform from your device. Use these examples in conjunction with the NI-DAQ Function Reference Manual, which can be downloaded from http://www.ni.com/manuals, and you will be able to better understand what is happening in these examples.
Regards,
Justin Britten