Cylinders 1 to 4 are in the right bank of the engine and 5 to 8 in the left bank.
Left and right are when looking forward from the rear of the vehicle.
Cylinders 4 & 8 are at the rear of the engine.
In other words, when you're looking under the bonnet stood in front of the vehicle, cylinder 1 is the one nearest to you on your left.