This is great, I've only just seen it!
Your chainring there is the outer ring, so if you want higher gears you would need another set of rings, bolts and proprietary washers between rings.
You probably know this but the chainring in the picture is off, i.e. not symmetrically fitted to the crank. If you keep rotating it there is a spot where the arm fits right in the middle of one of the slots on the chainring, if that makes sense.