The bolts all remove to give two plates (leave the top chainring type bolt loosely engaged to act as a hinge/pivot). Position it on the rear dropout so that both plates sit square to the frame and the wee 'foot' next to the chainring bolt sits against the seatstay. Feed the wheel axle through one on the holes, tighten down bolts and away you go! It really is quite simple.
Only thing is that the dropouts need to be flat - it won't work with fancy CNC'd pieces of art. I had it on my Zaskar and it fit perfectly.