Help with inputs for NARX net

whos inMat
  Name                Size               Bytes  Class     Attributes

  inMat      21x1200            201600  double              

>> whos tarMat
  Name               Size              Bytes  Class     Attributes

  tarMat      1x1200             9600  double              
  

these are INPUTS resp TARGETS for my NARXNET I am bit confused, is it a good way ? how could I test my net for new data ? how could I display predicted values from closed loop narx?