So after you define the model, on the sequencer tab , the model should show up , else you edit display elements and add the model to the master view.
You can create a view , add the model to that view and select that view to use . net result is that the model (ie LED) should show on your sequencer tab .
then you select the On effect and drop it on the sequencer against the model - stretch it for say 5 seconds.
Ensure that the color selected is White for the On effect (since you defined your model as White)
then drop an off effect after the on , followed by the On again. You can select an area and click d for Ramp down etc. Make sure that the color selected is White.
for it to appear in the Model preview window , select the On effect in the grid (ie where dropped against the model) and then press stop and then Play.
It should appear in the house preview window as soon s you press play.
for it to appear in the Layout tab , ensure that u press Render All or Save and then use the Play button of the layout tab.
If u delete or shrink the effect (and not replace that area) , click on render all