Hold the critter face of it pointing atcha.
On the side the side on your right, is a deeply recessed sliding switch.
Look at the slide switch. One direction is for 240 vac the other is for 120 vac.
Also note the 120 volt line voltage connections are not idiot touch-proof.
Push-comes-to-shove a correct flat bladed screwdriver works. No phillips fits the terminal screws - don't try it.
Figure out a way to connect the three positive connection points to one positive wire and do the same with the three negative wires. Feeding those screws inside the case are six copper circuit traces not heavy wires, My megas leaked voltage and made the case enlivened so these things really need that ground wire.
The following is a tip not hard and fast instructions. Go to google. Look for 14 (Fourteen) Gauge Silicone Wire. Sold black and red pairs. Five feet long each. use this wire to make your trident connections if you can Super fine stranded. It will lock down with the screws way better than standard wire in the terminal board. And when you go to trident the three wires into one, the soft wire makes it a snap. Ten gauge from there unless the wire run is longer tha 20' in which case I recommend 8 gauge. But a trident connection at the machine makes it very difficult to accidentally yank the power wires loose. I GOOPed adhesive the line, neutal and ground wires for shock proofing and pull loose resistance.
From the school of hard knocks.