He's clearly in the Material Room because if you open the image into another browser tab, the Poser Material tab is active.  Follow these instructions: Open the menu under Window in the Poser upper taskbar, go down to and click on Room Tools (should be third entry from the bottom), click on Material, and make sure the Material Palette is checked on.  Otherwise, it will not be open for use.  I suggest that you manually close Animation Controls, the Message Log panel, and perhaps the Display Style panel unless you really need it.  I never had any use for those in the Material Room and I've also closed the Parameter/Properties panel as well.  Your Preview Window is undocked so I recommend that you lock it down some place so it won't get in the way.